CN102239568A - Solar cell back sheet and solar cell module having same - Google Patents

Abstract

The back sheet (1) for a solar cell comprises a 1 st resin layer (11), a 2 nd resin layer (12), a 3 rd resin layer (13) and a 4 th resin layer (14) in this order, wherein the 1 st resin layer (11) is an infrared ray-transmitting colored resin layer, at least the 2 nd resin layer (12) of the 2 nd resin layer (12) and the 3 rd resin layer (13) is a white resin layer, the 4 th resin layer (14) is a back surface protective layer, and the thickness H of the 1 st resin layer (11)_AAnd the thickness H of the 2 nd resin layer (12)_BAnd the thickness H of the 3 rd resin layer (13)_CSatisfies the condition that is more than or equal to 0.4_A+H_C)/H_BH is not less than 2.4 and not more than 0.7_A/H_CLess than or equal to 1.3. A water vapor barrier layer may be provided between the 3 rd resin layer (13) and the 4 th resin layer (14).

Description

Solar cell back sheet and solar cell module having same

technical field

The present invention relates to a solar cell that has a dark-colored appearance, absorbs visible light when irradiated with light, and prevents heat storage by transmitting infrared rays, improves photoelectric conversion efficiency, and is excellent in flexibility, heat resistance, and damage resistance. A back sheet; a back sheet for a solar cell excellent in flexibility, heat resistance, water vapor barrier properties, and damage resistance; and a solar cell module including the back sheet for a solar cell.

Background technique

In recent years, solar cells have attracted attention as energy supply means instead of petroleum, which is an energy source that forms carbon dioxide that causes global warming. Demand for solar cells is also increasing, and stable supply and cost reduction of various components constituting solar cell modules included in solar cells have been sought. In addition, there is an increasing demand for improvement in the power generation efficiency of solar cells.

In a solar cell module, a plurality of plate-shaped solar cell elements are arranged, connected in series and in parallel, packaged to protect the elements, and unitized. In addition, the solar cell module generally has a structure in which the surface of the solar cell element exposed to sunlight is covered with a glass plate, and a composition containing, for example, an ethylene-vinyl acetate copolymer with high transparency and excellent moisture resistance is filled. A filler part is formed in the gap of the solar cell element, and the back surface (exposed surface of the filler part) is sealed with a member called a solar cell back sheet.

As a back sheet for a solar cell, a back sheet in which a white thermoplastic resin sheet is laminated on both sides of a polyester sheet is known in order to increase the reflectance of sunlight to increase the power generation efficiency of the solar cell (see Patent Documents 1 and 2).

When disposing the solar cell on the roof of a house, etc., it is preferable to be colored in a dark color such as black from the viewpoint of appearance, and therefore, a solar cell back sheet colored in a dark color is sought.

Carbon black is generally used as a solar cell back sheet colored in a dark color. In such an embodiment, the carbon black absorbs sunlight and the temperature rises, which may lower not only the power generation efficiency of the solar cell but also the durability.

In addition, as another solar cell back sheet, a sheet formed of a low heat storage thermoplastic resin composition containing a thermoplastic resin and an inorganic pigment having infrared reflection properties is known (see Patent Document 3).

Furthermore, there is known a back sheet for solar cells that has a black resin layer containing a perylene-based pigment on the surface, and that reflects near-infrared rays with a reflectance of 800 to 1,100 nm light of 30% or more, thereby preventing heat storage. (Refer to Patent Document 4).

Also, in a solar cell module including a solar cell back sheet, when water, water vapor, or the like intrudes from the solar cell back sheet side, degradation of solar cell elements and further reduction in power generation efficiency may be caused.

prior art literature

patent documents

Patent Document 1: JP-A-2006-270025

Patent Document 2: JP-A-2007-177136

Patent Document 3: JP-A-2007-103813

Patent Document 4: JP-A-2007-128943

Contents of the invention

The object of the present invention is to provide a solar cell that has a dark-colored appearance, a balance between flexibility and heat resistance (dimensional stability), excellent designability and damage resistance, suppresses heat storage by transmitting infrared rays, and can improve photoelectric conversion efficiency. A backplane and a solar cell module having the same.

In addition, another object of the present invention is to provide a product that has a dark-colored appearance, a balance and designability of flexibility and heat resistance (dimensional stability), excellent water vapor barrier properties and damage resistance, and suppresses heat storage through infrared rays. , A solar cell back sheet capable of improving photoelectric conversion efficiency, and a solar cell module having the same.

means to solve the problem

The present invention is shown below.

1. A back sheet for a solar cell, which is sequentially provided with a first resin layer, a second resin layer, a third resin layer, and a fourth resin layer, wherein the first resin layer is an infrared-transmitting colored resin layer, and the above-mentioned Of the second resin layer and the third resin layer, at least the second resin layer is a white-based resin layer, the fourth resin layer is a back protection layer, and the thickness (H A ) of the first resin layer and the thickness (H _A ) of the second resin layer are The thickness (H _B ) of the resin layer and the thickness (H _C ) of the third resin layer satisfy the following formulas (1) and (2).

0.4≤(H _A +H _C )/H _B ≤2.4 (1)

0.7≤H _A /H _C ≤1.3 (2)

2. The back sheet for solar cells as described in 1 above, wherein the thermoplastic resin constituting the first resin layer, the thermoplastic resin constituting the second resin layer, and the thermoplastic resin constituting the third resin layer are all aromatic-containing Thermoplastic resin of family vinyl resin.

3. The backsheet for solar cells as described in 2 above, wherein the glass transition temperature of the thermoplastic resin constituting the first resin layer and the glass transition temperature of the thermoplastic resin constituting the third resin layer are both higher than those of the constituents. The thermoplastic resin of the second resin layer has a low glass transition temperature.

4. The back sheet for solar cells according to any one of 1 to 3 above, wherein when light having a wavelength of 400 to 700 nm is radiated on the surface of the first resin layer in the back sheet for solar cells, The absorptivity of the above-mentioned light is 60% or more.

5. The back sheet for solar cells according to any one of 1 to 4 above, wherein when light having a wavelength of 800 to 1,400 nm is radiated on the surface of the first resin layer in the back sheet for solar cells, the The reflectance of the above-mentioned light is 50% or more.

6. The solar cell backsheet according to any one of 1 to 5 above, wherein the fourth resin layer is a flame-retardant resin layer.

7. The solar cell back sheet according to any one of 1 to 6 above, further comprising a water vapor barrier layer between the third resin layer and the fourth resin layer.

8. The solar cell back sheet according to the above 7, wherein the water vapor barrier layer is formed of a vapor-deposited film formed by forming a film containing a metal and/or a metal oxide on its surface.

9. The solar cell back sheet according to the above 7 or 8, wherein an adhesive layer is provided between the third resin layer and/or the fourth resin layer and the water vapor barrier layer.

10. The solar cell backsheet according to any one of 1 to 9 above, wherein the rate of dimensional change when left at 150° C. for 30 minutes is ±1% or less.

11. The back sheet for solar cells according to any one of 1 to 10 above, wherein the back sheet for solar cells has a thickness of 50 to 1,000 μm.

12. A solar cell module comprising the solar cell back sheet according to any one of 1 to 11 above.

The effect of the invention

According to the backsheet for solar cells of the present invention, the balance between flexibility and heat resistance (dimensional stability), designability and scratch resistance are excellent, and heat storage can be suppressed by transmitting infrared rays through the first resin layer, and photoelectric conversion can be improved. efficiency.

In addition, according to the solar cell back sheet of the present invention having a water vapor barrier layer between the third resin layer and the fourth resin layer, the balance between flexibility and heat resistance (dimensional stability), designability, and water vapor barrier It is excellent in durability and damage resistance, and can suppress heat storage by transmitting infrared rays in the first resin layer, and can improve photoelectric conversion efficiency.

When the thermoplastic resin constituting the first resin layer, the thermoplastic resin constituting the second resin layer, and the thermoplastic resin constituting the third resin layer are all thermoplastic resins containing an aromatic vinyl resin, hydrolysis resistance, Dimensional stability, impact resistance, etc. are excellent.

When both the glass transition temperature of the thermoplastic resin constituting the first resin layer and the glass transition temperature of the thermoplastic resin constituting the third resin layer are lower than the glass transition temperature of the thermoplastic resin constituting the second resin layer Under this condition, it is possible to suppress cracking when bent, and achieve a balance between heat resistance and flexibility.

When light having a wavelength of 400 to 700 nm is radiated to the surface of the first resin layer in the solar cell back sheet, the absorptance of the light is 60% or more, and a solar cell module excellent in dark color appearance can be provided. Therefore, when a solar cell module including this sheet is placed on a roof of a house or the like, excellent appearance, design, and the like can be obtained.

When light having a wavelength of 800 to 1,400 nm is radiated to the surface of the first resin layer in the solar cell back sheet, and the reflectance of the light is 50% or more, sunlight is emitted from adjacent solar cell elements. When the gap leaks to the side of the solar cell back sheet through the filler part containing the polymer composition or the like embedded in the solar cell element, the heat storage of the solar cell back sheet is suppressed. Furthermore, reflected light can be made incident on the solar cell element, and power generation efficiency can be improved.

When the above-mentioned water vapor barrier layer is composed of a vapor-deposited film formed by forming a film containing metal and/or metal oxide on its surface, the balance of flexibility and heat resistance (dimensional stability) is not lowered, and water vapor Excellent barrier properties.

When the dimensional change rate of the back sheet for a solar cell of the present invention is ±1% or less when left to stand at 150° C. for 30 minutes, it is excellent in heat resistance.

When the thickness of the said back sheet for solar cells is 50-1,000 micrometers, it is excellent in flexibility.

According to the solar cell module of the present invention, since it is provided with the solar cell backsheet of the present invention, it is possible to form a solar cell having excellent appearance, design, heat resistance, weather resistance, and damage resistance, and improved photoelectric conversion efficiency. . This solar cell is preferably used outdoors where it is exposed to sunlight, wind and rain for a long time.

Description of drawings

FIG. 1 is a schematic cross-sectional view showing an example of a solar cell backsheet.

Fig. 2 is a schematic cross-sectional view showing another example of a solar cell back sheet.

Fig. 3 is a schematic cross-sectional view showing an example of the solar cell module of the present invention.

Detailed ways

Hereinafter, the present invention will be described in detail. In this specification, "(co)polymerization" means homopolymerization and copolymerization. In addition, "(meth)acrylic" means acrylic and methacrylic, and "(meth)acrylate" means acrylate and methacrylate.

The backsheet for solar cells of the present invention is a sheet provided with a first resin layer, a second resin layer, a third resin layer, and a fourth resin layer in this order, and a schematic cross-sectional example thereof is shown in FIG. 1 . That is, the backsheet 1A for solar cells in FIG. 1 is a laminated sheet including a first resin layer 11 , a second resin layer 12 , a third resin layer 13 , and a fourth resin layer 14 in this order.

In addition, the solar cell backsheet of the present invention may include a water vapor barrier layer between the third resin layer and the fourth resin layer, and a schematic cross-sectional example thereof is shown in FIG. 2 . That is, the backsheet 1B for solar cells in FIG. 2 is a laminated sheet including a first resin layer 11 , a second resin layer 12 , a third resin layer 13 , a water vapor barrier layer 15 , and a fourth resin layer 14 in this order.

The backsheet for solar cells of the present invention is formed in order to bond the surface (upper side) of the first resin layer 11 to the exposed surface of the filler part containing ethylene-vinyl acetate copolymer composition or the like for encapsulating solar cell elements. use.

The above-mentioned first resin layer is an infrared transparent colored resin layer bonded to the exposed surface of the filler portion for embedding the solar cell element, and is preferably made of a thermoplastic resin (hereinafter referred to as "thermoplastic resin (I)") and A thermoplastic resin composition (hereinafter referred to as "the first thermoplastic resin composition") of a colorant (hereinafter referred to as "infrared transparent colorant") having the property of absorbing visible light and transmitting infrared rays (hereinafter referred to as "the first thermoplastic resin composition") obtained layer. In addition, the first resin layer is a layer that absorbs visible light while transmitting infrared rays in the solar cell back sheet of the present invention to impart coloring and flexibility to the sheet.

The above-mentioned second resin layer is a white-based resin layer, and it is preferable to use a coloring agent (hereinafter referred to as "white resin (II)" containing a thermoplastic resin (hereinafter referred to as "thermoplastic resin (II)") and having the property of reflecting visible light and infrared rays. A layer obtained from a thermoplastic resin composition (hereinafter referred to as "the second thermoplastic resin composition"). Furthermore, the second resin layer is a base layer of the solar cell back sheet of the present invention, and is a heat-resistant layer, and further, has a function of reflecting infrared rays transmitted through the first resin layer, and has heat resistance. layer.

The third resin layer is preferably a layer obtained by using a thermoplastic resin composition (hereinafter referred to as "third thermoplastic resin composition") containing a thermoplastic resin (hereinafter referred to as "thermoplastic resin (III)"). And, this third resin layer is a layer that imparts flexibility to the solar cell back sheet of the present invention. In addition, when the said 3rd thermoplastic resin composition contains a white coloring agent, when infrared rays pass through a 2nd resin layer, this infrared ray can be reflected from a 3rd resin layer.

In addition, the above-mentioned fourth resin layer is a back protective layer, and it is preferable to use a thermoplastic resin composition (hereinafter referred to as "the fourth thermoplastic resin composition") containing a thermoplastic resin (hereinafter also referred to as "thermoplastic resin (IV)"). .) and the resulting layer. And this 4th resin layer is the back sheet for solar cells of the present invention that suppresses damage, deterioration, etc. caused by the impact, heat, chemical substances, etc. caused by the force from the back, and imparts a function to the solar cell module equipped with the back sheet for solar cells. The layer that plays a role such as durability.

It should be noted that, as described above, the solar cell back sheet of the present invention may be a back sheet provided with a water vapor barrier layer. In this case, the water vapor barrier layer can be mainly protected by the fourth resin layer, and it is possible to suppress damage, deterioration, etc. caused by impact, heat, chemical substances, etc. caused by force from the back, and provide a solar cell module with a back sheet for solar cells. With durability etc.

The first thermoplastic resin composition, the second thermoplastic resin composition, the third thermoplastic resin composition, and the fourth thermoplastic resin composition are preferably compositions having film-forming properties.

The glass transition temperature (hereinafter referred to as "Tg") of the thermoplastic resin (I) contained in the first thermoplastic resin composition is preferably from the viewpoint of imparting flexibility to the solar cell back sheet of the present invention. 90°C to 200°C, more preferably 95°C to 180°C, still more preferably 100°C to 170°C, particularly preferably 105°C to 160°C.

The Tg of the thermoplastic resin (II) contained in the second thermoplastic resin composition is preferably 110°C to 220°C, more preferably 120°C, from the viewpoint of imparting heat resistance to the solar cell back sheet of the present invention. to 200°C, more preferably 130°C to 190°C.

In addition, the Tg of the thermoplastic resin (III) contained in the third thermoplastic resin composition is preferably 90°C to 200°C, more preferably 95°C, from the viewpoint of imparting flexibility to the solar cell back sheet of the present invention. ~180°C, more preferably 100°C to 170°C, particularly preferably 105°C to 160°C.

The above Tg can be measured with a differential scanning calorimeter (DSC).

In the back sheet for solar cells of the present invention, preferred embodiments for obtaining excellent heat resistance and flexibility are as follows. That is, Tg of the thermoplastic resin (I) and Tg of the thermoplastic resin (III) are equal to or lower than Tg of the thermoplastic resin (II). In order to impart sufficient flexibility to the board, Tg of the thermoplastic resin (I) and Tg of the thermoplastic resin (III) are preferably lower than Tg of the thermoplastic resin (II). The difference between the Tg of the thermoplastic resin (I) and the Tg of the thermoplastic resin (II) is preferably 10°C or higher, more preferably 15°C or higher, and the difference between the Tg of the thermoplastic resin (II) and the Tg of the thermoplastic resin (III) is preferably 10°C or higher, more preferably 15°C or higher.

When two or more kinds of thermoplastic resins are contained in each resin layer and a plurality of Tgs are obtained from a DSC curve, a higher Tg is adopted.

Each layer will be described in order below.

The thermoplastic resin (I) contained in the first thermoplastic resin composition forming the first resin layer (infrared transparent colored resin layer) is not particularly limited as long as it is a thermoplastic resin. Examples of the thermoplastic resin (I) constituting the first resin layer include aromatic vinyl resins, polyolefin resins, polyvinyl chloride resins, polyvinylidene chloride resins, polyvinyl acetate resins, saturated polyester resins, Polycarbonate resins, acrylic resins (such as (co)polymers of (meth)acrylate compounds), fluororesins, ethylene/vinyl acetate resins, and the like. These compounds may be used alone or in combination of two or more. In addition, among the above-mentioned compounds, aromatic vinyl resins are preferable from the viewpoint of hydrolysis resistance and dimensional stability.

The above-mentioned aromatic vinyl resin is a rubber-reinforced aromatic vinyl resin obtained by polymerizing an aromatic vinyl compound in the presence of a rubbery polymer; (co)polymers made of vinyl monomers of vinyl compounds, etc. In the present invention, the above-mentioned aromatic vinyl resin is preferably a rubber-reinforced aromatic vinyl resin. When the above-mentioned thermoplastic resin (I) contains a rubber-reinforced aromatic vinyl resin, it is possible to form a first resin layer excellent in hydrolysis resistance, dimensional stability, and impact resistance.

Examples of the above-mentioned aromatic vinyl-based resins include rubber-reinforced aromatic vinyl resins obtained by polymerizing a vinyl-based monomer (b11) containing an aromatic vinyl compound in the presence of a rubbery polymer (a11). resin (I-1), a (co)polymer (I-2) of a vinyl monomer (b12) containing an aromatic vinyl compound, and a rubber-reinforced aromatic vinyl resin (I-1) and A mixture of (co)polymers (I-2).

The above-mentioned rubber-reinforced aromatic vinyl resin (I-1) generally contains: a copolymer resin in which a vinyl monomer (b11) containing an aromatic vinyl compound is graft-copolymerized with a rubbery polymer (a11), and A (co)polymer obtained by non-grafting of the rubbery polymer (a11), that is, the remaining vinyl monomer (b11).

The aromatic vinyl resin described above preferably contains at least one rubber-reinforced aromatic vinyl resin (I-1), particularly preferably one or more rubber-reinforced aromatic vinyl resins (I-1). , or a combination of one or more rubber-reinforced aromatic vinyl resins (I-1) and one or more of the aforementioned (co)polymers (I-2). In these cases, the content of the rubbery polymer (a11) in the aromatic vinyl resin is preferably 5 to 40% by mass, More preferably, it is 8-30 mass %, More preferably, it is 10-20 mass %, Especially preferably, it is 12-18 mass %. When the said content exceeds 40 mass %, heat resistance may become insufficient, and it may become difficult to use the 1st resin layer of a 1st thermoplastic resin composition. On the other hand, when the said content is less than 5 mass %, flexibility may become insufficient.

The rubber-like polymer (a11) used for forming the rubber-reinforced aromatic vinyl-based resin (I-1) is not particularly limited as long as it is rubbery at room temperature, and may be either a homopolymer or a copolymer. kind. In addition, the rubbery polymer (a11) may be either a crosslinked polymer or a non-crosslinked polymer.

The aforementioned rubbery polymer (a11) is not particularly limited, and examples thereof include conjugated diene rubber, hydrogenated conjugated diene rubber, ethylene/α-olefin copolymer rubber, acrylic rubber, silicone rubber, Silicone-acrylic composite rubber, etc. These compounds may be used alone or in combination of two or more.

Among the above-mentioned compounds, conjugated diene-based rubbers are preferable from the viewpoint of impact resistance, and acrylic rubbers, silicone rubbers, silicone-acrylic composite rubbers, and ethylene-α-olefin-based rubbers are preferable from the viewpoint of weather resistance. Copolymer rubber and hydrogenated conjugated diene rubber.

The shape of the above-mentioned rubbery polymer (a11) is not particularly limited, and may be particulate (spherical, substantially spherical), linear, curved, or the like. In the case of particles, the volume average particle diameter thereof is preferably 5 to 2,000 nm, more preferably 10 to 1,800 nm, and still more preferably 50 to 1,500 nm. When the volume average particle diameter is within the above range, the processability of the first thermoplastic resin composition, the impact resistance of the obtained first resin layer, and the like are excellent. In addition, the said volume average particle diameter can be measured by image analysis using an electron micrograph, a laser diffraction method, a light scattering method, etc.

Examples of the conjugated diene rubber include polybutadiene, butadiene-styrene random copolymers, butadiene-styrene block copolymers, butadiene-acrylonitrile copolymers, and the like. These compounds may be used alone or in combination of two or more.

In the present invention, the above-mentioned conjugated diene rubber preferably has a glass transition temperature of -20°C or lower from the viewpoint of flexibility, low-temperature impact properties, and the like.

The acrylic rubber is preferably a (co)polymer containing 80% by mass or more of a structural unit derived from an alkyl group having 2 to 8 carbon atoms, based on the total amount of structural units constituting the acrylic rubber.

Examples of alkyl acrylates having 2 to 8 carbon atoms in the alkyl group include ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, hexyl acrylate, n-octyl acrylate, 2-ethyl acrylate, Hexyl ester, etc. These compounds may be used alone or in combination of two or more. Preferred alkyl acrylates are n-butyl acrylate, isobutyl acrylate and 2-ethylhexyl acrylate.

When the above-mentioned acrylic rubber contains structural units derived from other monomers, examples of other monomers include vinyl chloride, vinylidene chloride, acrylonitrile, vinyl ester, alkyl methacrylate, (methyl ) monofunctional monomers such as acrylic acid and styrene; ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, Mono- or polyethylene glycol di(meth)acrylates such as diol di(meth)acrylates; divinylbenzene, diallyl phthalate, diallyl maleate, Di- or triallyl compounds such as diallyl succinate, triallyl triazine, etc.; allyl compounds such as allyl (meth)acrylate; conjugated 1,3-butadiene, etc. Cross-linkable monomers such as diene compounds, etc.

In the present invention, the acrylic rubber preferably has a glass transition temperature of -10°C or lower from the viewpoint of flexibility, low-temperature impact properties, and the like. The acrylic rubber having the above-mentioned glass transition temperature is usually a copolymer containing a structural unit derived from the above-mentioned crosslinkable monomer.

Preferably, the content of the structural unit derived from the crosslinkable monomer constituting the acrylic rubber is preferably 0.01 to 10% by mass, more preferably 0.05 to 8% by mass, and even more preferably 0.1 to 10% by mass based on the total amount of the structural unit. 5% by mass.

The volume average particle diameter of the acrylic rubber is preferably 5 to 500 nm, more preferably 10 to 450 nm, and still more preferably 20 to 400 nm from the viewpoint of flexibility and low-temperature impact properties.

The above-mentioned acrylic rubber can be produced by a known method, and a preferred production method is an emulsion polymerization method.

As the above-mentioned silicone rubber, in order to facilitate emulsion polymerization, which is a preferred method for producing the rubber-reinforced aromatic vinyl resin (I-1), rubber contained in latex is preferable. Therefore, the silicone rubber may be, for example, a polyorganosiloxane-based rubber produced by the method described in US Patent No. 2,891,920, US Patent No. 3,294,725, or the like.

The above polyorganosiloxane-based rubber, for example, is preferably a silicone rubber that is mixed in the presence of a sulfonic acid-based emulsifier such as alkylbenzenesulfonic acid or alkylsulfonic acid using a homomixer or an ultrasonic mixer. Silicone rubber contained in a latex obtained by shear mixing organosiloxane and water followed by condensation. Alkylbenzenesulfonic acid is preferable since it functions as an emulsifier of organosiloxane and also as a polymerization initiator. At this time, if metal alkylbenzenesulfonate, metal alkylsulfonate, etc. are used in combination, there is an effect of stably maintaining the silicone rubber when producing the rubber-reinforced aromatic vinyl resin (I-1). preferred. In addition, the polymer terminal of the above-mentioned polyorganosiloxane-based rubber may be blocked with, for example, a hydroxyl group, an alkoxy group, a trimethylsilyl group, a methyldiphenylsilyl group, or the like. In addition, if necessary, a graft crossing agent and/or a crosslinking agent may be co-condensed within a range not impairing the target performance of the present invention. By using them, impact resistance can be improved.

The organosiloxane used in the above reaction is, for example, a compound having a structural unit represented by the following general formula (1).

[R ¹ _m SiO _(4-m)/2 ] (1)

(In the formula, R ¹ is a substituted or unsubstituted monovalent hydrocarbon group, and m represents an integer of 0 to 3.)

The structure of the compound represented by the general formula (1) is linear, branched or cyclic, and the compound is preferably an organosiloxane having a cyclic structure. Examples of R ¹ that this organosiloxane has, that is, monovalent hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, and butyl; aryl groups such as phenyl and tolyl; vinyl, allyl, etc.; Alkenyl groups such as alkenyl groups; and groups in which some of the hydrogen atoms bonded to carbon atoms in these hydrocarbon groups are replaced by halogen atoms, cyano groups, etc.; and groups in which at least one of the hydrogen atoms in alkyl groups is replaced by mercapto groups, etc. .

As the organosiloxane mentioned above, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, trimethyltriphenyl In addition to cyclic compounds such as phenylcyclotrisiloxane, tetramethyltetraphenylcyclotetrasiloxane, and octaphenylcyclotetrasiloxane, straight-chain or branched-chain organosiloxanes can be used. These compounds may be used alone or in combination of two or more.

In addition, the said organosiloxane may be polyorganosiloxane condensed in advance, for example, Mw of about 500-10,000. In addition, when the organosiloxane is a polyorganosiloxane, its molecular chain terminal may be blocked with a hydroxyl group, an alkoxy group, a trimethylsilyl group, a methyldiphenylsilyl group, or the like.

The above-mentioned graft crossing agent is usually a compound having a carbon-carbon unsaturated bond and an alkoxysilyl group, for example p-vinylphenylmethyldimethoxysilane, 2-(p-vinylphenyl ) ethylmethyldimethoxysilane, 3-(p-vinylbenzoyloxy)propylmethyldimethoxysilane, etc.

The usage-amount of the above-mentioned graft crossing agent is usually 10 mass parts or less, preferably 0.2 to 10 mass parts or more, when the total of organosiloxane, graft crossing agent and crosslinking agent is taken as 100 mass %. Preferably it is 0.5-5 mass parts. When the usage-amount of the said graft crossing agent is too large, the molecular weight of a graft copolymer will fall, and as a result, sufficient impact resistance may not be acquired. In addition, due to the double bond of the grafted polyorganosiloxane-based rubber, oxidative deterioration is likely to occur, and a rubber-reinforced aromatic vinyl-based resin having good weather resistance may not be obtained.

Examples of the crosslinking agent include trifunctional crosslinking agents such as methyltrimethoxysilane, ethyltrimethoxysilane, phenyltrimethoxysilane, and ethyltriethoxysilane; tetraethoxysilane and other 4-functional cross-linking agents, etc. In addition, you may use the crosslinkable prepolymer which polycondensed these compounds beforehand. These compounds may be used alone or in combination of two or more.

The amount of the crosslinking agent used is usually 10 parts by mass or less, preferably 5 parts by mass or less, more preferably 0.01 to 5 parts by mass. When the usage-amount of the said crosslinking agent is too large, the flexibility of the polyorganosiloxane rubber obtained may be impaired, and the flexibility of a board may fall.

The volume average particle diameter of the silicone rubber is usually 5 to 500 nm, preferably 10 to 400 nm, more preferably 50 to 400 nm. The volume average particle diameter can be easily controlled by the amount of emulsifier and water used during production, the degree of dispersion during mixing using a homomixer or ultrasonic mixer, or the method of adding organosiloxane. When the volume average particle diameter exceeds 500 nm, the appearance may be deteriorated, such as gloss reduction.

The aforementioned silicone-acrylic composite rubber is a rubbery polymer containing polyorganosiloxane rubber and polyalkyl(meth)acrylate rubber. A preferable silicone-acrylic composite rubber is a composite rubber having a structure in which polyorganosiloxane rubber and polyalkyl(meth)acrylate rubber are entangled with each other without separation.

As the polyorganosiloxane-based rubber, rubber obtained by copolymerizing organosiloxane can be preferably used. Examples of the above-mentioned organosiloxane include various reducing forms of three-membered or more rings, among which hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclopentasiloxane, etc. Methylcyclohexasiloxane, trimethyltriphenylcyclotrisiloxane, tetramethyltetraphenylcyclotetrasiloxane, octaphenylcyclotetrasiloxane, etc. Furthermore, these organosiloxanes may be used alone or in combination of two or more.

The content of organosiloxane-derived structural units constituting the polyorganosiloxane-based rubber is preferably 50% by mass or more, more preferably 70% by mass or more, based on the total amount of the structural units.

As the above-mentioned acrylic rubber, it is preferable to contain methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, ethoxyethoxyethyl acrylate, methoxy Rubber obtained by (co)polymerizing monomers of alkyl (meth)acrylate compounds such as tripropylene glycol acrylate, 4-hydroxybutyl acrylate, lauryl methacrylate, and stearyl methacrylate. These alkyl (meth)acrylate compounds may be used alone or in combination of two or more.

In addition, the above-mentioned monomers may contain aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, etc. in a range of 30% by mass or less in addition to alkyl (meth)acrylate compounds; propylene Cyanide vinyl compounds such as nitrile and methacrylonitrile; various vinyl monomers such as methacrylic acid-modified silicone and fluorine-containing vinyl compounds as copolymerization components.

The above-mentioned acrylic rubber is preferably a copolymer having two or more glass transition temperatures from the viewpoint of being able to impart sufficient flexibility to the board.

As the above-mentioned silicone-acrylic composite rubber, for example, rubbers produced by the methods described in JP-A-4-239010 and JP-A-4-100812 can be used.

The volume average particle diameter of the silicone-acrylic composite rubber is preferably 5 to 500 nm, more preferably 10 to 450 nm, and still more preferably 20 to 400 nm from the viewpoint of flexibility and low-temperature impact properties.

The above-mentioned ethylene·α-olefin copolymer rubber is a copolymer containing an ethylene unit and a unit formed of an α-olefin having a carbon number of 3 or more, examples of which include ethylene·α-olefin copolymer, ethylene·α-olefin non- Conjugated diene copolymers, etc.

Examples of the above-mentioned ethylene/α-olefin copolymers include ethylene/propylene copolymers, ethylene/butene-1 copolymers, and the like. In addition, examples of the above-mentioned ethylene·α-olefin·non-conjugated diene copolymer include ethylene·propylene·non-conjugated diene copolymer, ethylene·butene-1·non-conjugated diene copolymer, and the like.

The above-mentioned α-olefins are preferably α-olefins having 3 to 20 carbon atoms, specifically, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1 -Heptene, 1-octene, 1-decene, 1-dodecene, 1-hexadecene, 1-eicosene, etc. Among the above-mentioned α-olefins, the carbon number is more preferably 3-12, more preferably 3-8.

The ratios of ethylene units and α-olefin units constituting the above-mentioned ethylene·α-olefin copolymer rubber are preferably 5 to 95% by mass and 5 to 95% by mass, respectively, when the total of these units is taken as 100% by mass. %, more preferably 50-90% by mass and 10-50% by mass, still more preferably 60-88% by mass and 12-40% by mass, particularly preferably 70-85% by mass and 15-30% by mass. When the content rate of the said α-olefin unit is too large, flexibility may fall.

When the above-mentioned ethylene-α-olefin-based copolymer rubber is an ethylene-α-olefin-non-conjugated diene copolymer, examples of the non-conjugated diene include 5-ethylidene-2-norbornene alkenyl norbornene, etc.; cyclic dienes, such as dicyclopentadiene; aliphatic dienes, etc. These compounds may be used alone or in combination of two or more.

The content of the structural unit derived from the above-mentioned non-conjugated diene is preferably 1 to 30% by mass, more preferably 2 to 30% by mass relative to the total amount of structural units constituting the above-mentioned ethylene·α-olefin·non-conjugated diene copolymer. 20% by mass. When the content ratio of the non-conjugated diene unit is too large, the molded appearance and weather resistance may decrease.

The amount of unsaturated groups in the ethylene/α-olefin-based copolymer rubber is preferably 4-40 in terms of iodine value.

The Mooney viscosity (ML ₁₊₄ , 100°C; based on JIS K6300) of the ethylene·α-olefin copolymer rubber is preferably 5-80, more preferably 10-65, and still more preferably 15-45. When the Mooney viscosity is within the above range, impact resistance and flexibility are excellent.

The hydrogenated conjugated diene rubber is not particularly limited as long as it is a (co)polymer obtained by hydrogenating a (co)polymer containing a structural unit derived from a conjugated diene compound.

Examples of the hydrogenated conjugated diene rubber include hydrogenated products of conjugated diene block copolymers having the following structures. That is, it is a block copolymer comprising a combination of two or more polymer blocks of the following polymer blocks: a polymer block A composed of a structural unit derived from an aromatic vinyl compound; A polymer block B obtained by hydrogenating 95 mol% or more of the double bonds of the structural units of the conjugated diene compound with a 1,2-vinyl bond content of more than 25 mol%; it will contain 1,2- A polymer block C obtained by hydrogenating 95 mol% or more of the double bond portion of a polymer of structural units of a conjugated diene compound having a vinyl bond content of 25 mol% or less; Polymer block D obtained by hydrogenating 95 mol% or more of the double bond portion of the copolymer of the structural unit and the structural unit derived from the conjugated diene compound.

The molecular structure of the above-mentioned block copolymer may be branched, radial or a combination thereof. In addition, the block structure may be diblock, triblock, multiblock or combinations thereof.

Examples of the structure of the block copolymer include A-(B-A)n, (A-B)n, A-(B-C)n, C-(B-C)n, (B-C)n, A-(D-A)n, (A-D)n, A-(D-C)n, C-(D-C)n, (D-C)n, A-(B-C-D)n, (A-B-C-D)n [wherein, n is an integer of 1 or more. ] etc., preferably A-B-A, A-B-A-B, A-B-C, A-D-C, C-B-C.

The aromatic vinyl compound used to form the polymer blocks A and D constituting the block copolymer is not particularly limited as long as it has at least one vinyl bond and at least one aromatic ring. Examples thereof include styrene, α-methylstyrene, methylstyrene, vinylxylene, monochlorostyrene, dichlorostyrene, monobromostyrene, dibromostyrene, fluorostyrene , p-tert-butylstyrene, ethylstyrene, vinylnaphthalene, etc. These compounds may be used alone or in combination of two or more. In addition, among these compounds, styrene is preferable.

The content ratio of the polymer block A constituting the block copolymer is preferably 0 to 65% by mass, more preferably 10 to 40% by mass, based on the entire polymer. When the content of the polymer block A is too large, the impact resistance may be insufficient.

The aforementioned polymer blocks B, C, and D are formed by hydrogenating a pre-hydrogenated block copolymer obtained using a conjugated diene compound and an aromatic vinyl compound. Examples of conjugated diene compounds that can be used in the formation of the above-mentioned polymer blocks B, C, and D include 1,3-butadiene, isoprene, 1,3-pentadiene, chlorine butadiene etc. These compounds may be used alone or in combination of two or more. In addition, among these compounds, 1,3-butadiene and isoprene are preferable because they can be used industrially and have excellent physical properties.

The hydrogenation rates of the above-mentioned polymer blocks B, C, and D are all 95 mol% or more, preferably 96 mol% or more.

The 1,2-vinyl bond content in the above-mentioned polymer block B is preferably more than 25 mol % and not more than 90 mol %, more preferably 30 to 80 mol %. When the 1,2-vinyl bond content is 25 mol% or less, the properties of rubber may be lost and the impact resistance may be insufficient. On the other hand, when it exceeds 90 mol%, chemical resistance may be insufficient.

In addition, the 1,2-vinyl bond content in the polymer block C is preferably 25 mol% or less, more preferably 20 mol% or less.

The 1,2-vinyl bond content in the polymer block D is preferably 25 to 90 mol%, more preferably 30 to 80 mol%. When the 1,2-vinyl bond content is less than 25% by mole, properties of rubber may be lost and impact resistance may be insufficient. On the other hand, when it exceeds 90 mol%, chemical resistance may be insufficient.

In addition, the amount of the aromatic vinyl compound unit in the above polymer block D is preferably 25% by mass or less, more preferably 20% by mass or less. When the amount of the aromatic vinyl compound unit exceeds 25% by mass, the properties of rubber may be lost and the impact resistance may be insufficient.

Examples of the hydrogenated conjugated diene rubber include hydrogenated polybutadiene, hydrogenated styrene-butadiene rubber, styrene-ethylene-butylene-olefin crystalline block polymer, olefin crystal-ethylene-butylene-olefin Crystalline block polymers, styrene-ethylene-butylene-styrene block polymers, hydrogenated butadiene-acrylonitrile copolymers, etc.

The weight average molecular weight (Mw) of the hydrogenated conjugated diene rubber is preferably 10,000 to 1 million, more preferably 30,000 to 800,000, and still more preferably 50,000 to 500,000. When Mw is in the above-mentioned range, flexibility is excellent.

Next, the vinyl monomer (b11) used for forming the rubber-reinforced aromatic vinyl resin (I-1) contains an aromatic vinyl compound. That is, the vinyl monomer (b11) may be a monomer composed of only an aromatic vinyl compound, or may be a monomer composed of an aromatic vinyl compound and another monomer copolymerizable with the compound. Examples of other monomers include vinyl cyanide compounds, (meth)acrylate compounds, maleimide-based compounds, unsaturated acid anhydrides, carboxyl-containing unsaturated compounds, hydroxyl-containing unsaturated compounds, ring-containing Oxygen unsaturated compounds, oxazoline group-containing unsaturated compounds, etc. These compounds may be used alone or in combination of two or more.

The above-mentioned aromatic vinyl compound is not particularly limited as long as it is a compound having at least one vinyl bond and at least one aromatic ring. Examples thereof include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, β-methylstyrene, ethylstyrene, p-tert-butylstyrene, vinyl Toluene, vinyl xylene, vinyl naphthalene, monochlorostyrene, dichlorostyrene, monobromostyrene, dibromostyrene, tribromostyrene, fluorostyrene, etc. These compounds may be used alone or in combination of two or more. In addition, among these compounds, styrene and α-methylstyrene are preferable, and styrene is particularly preferable.

Examples of the vinyl cyanide compound include acrylonitrile, methacrylonitrile, ethacrylonitrile, α-ethylacrylonitrile, α-isopropylacrylonitrile, α-chloroacrylonitrile, α-fluoroacrylonitrile wait. These compounds may be used alone or in combination of two or more. In addition, among these compounds, acrylonitrile is preferable.

Examples of the (meth)acrylate compounds include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, (meth)acrylate, ) n-butyl acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-Ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, etc. These compounds may be used alone or in combination of two or more.

Examples of the maleimide-based compounds include maleimide, N-methylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-dodecylmaleimide, N-phenylmaleimide, N-(2-methylphenyl)maleimide, N-(4-methylphenyl)maleimide imide, N-(2,6-dimethylphenyl)maleimide, N-(2,6-diethylphenyl)maleimide, N-(2-methoxy Phenyl)maleimide, N-benzylmaleimide, N-(4-hydroxyphenyl)maleimide, N-naphthylmaleimide, N-cyclohexylmaleimide imide etc. Among these compounds, N-phenylmaleimide is preferred. In addition, these compounds may be used alone or in combination of two or more. It should be noted that, as another method for introducing a structural unit derived from a maleimide compound into the above-mentioned rubber-reinforced aromatic vinyl resin (I-1), for example, an unsaturated dicarboxylic acid of maleic anhydride may be used. A method of imidization after copolymerization of acid anhydride.

Maleic anhydride, itaconic anhydride, citraconic anhydride etc. are mentioned as said unsaturated acid anhydride. These compounds may be used alone or in combination of two or more.

Examples of the carboxyl group-containing unsaturated compound include (meth)acrylic acid, ethacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, and cinnamic acid. These compounds may be used alone or in combination of two or more.

Examples of the unsaturated compound containing a hydroxyl group include 2-hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-Hydroxypropyl, 2-Hydroxybutyl (meth)acrylate, 3-Hydroxybutyl (meth)acrylate, 4-Hydroxybutyl (meth)acrylate, Polyethylene glycol mono(meth)acrylate , polypropylene glycol mono(meth)acrylate, and (meth)acrylates with hydroxyl groups such as compounds obtained by adding ε-caprolactone to 2-hydroxyethyl (meth)acrylate; o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, o-hydroxy-α-methylstyrene, m-hydroxy-α-methylstyrene, p-hydroxy-α-methylstyrene, 2-hydroxymethyl-α-methyl Styrene, 3-Hydroxymethyl-α-methylstyrene, 4-Hydroxymethyl-α-methylstyrene, 4-Hydroxymethyl-1-vinylnaphthalene, 7-Hydroxymethyl-1-ethylene Naphthalene, 8-hydroxymethyl-1-vinylnaphthalene, 4-hydroxymethyl-1-isopropenylnaphthalene, 7-hydroxymethyl-1-isopropenylnaphthalene, 8-hydroxymethyl-1-isopropenylnaphthalene Propyl naphthalene, p-vinyl benzyl alcohol, 3-hydroxy-1-propene, 4-hydroxy-1-butene, cis-4-hydroxy-2-butene, trans-4-hydroxy-2-butene, 3 -Hydroxy-2-methyl-1-propene and the like. These compounds may be used alone or in combination of two or more.

Examples of the above-mentioned epoxy group-containing unsaturated compound include glycidyl (meth)acrylate, 3,4-oxycyclohexyl (meth)acrylate, vinyl glycidyl ether, allyl glycidyl ether, methallyl glycidyl ether, etc. These compounds may be used alone or in combination of two or more.

Vinyl oxazoline etc. are mentioned as said oxazoline group containing unsaturated compound.

In the present invention, the above-mentioned vinyl monomer (b11) preferably contains an aromatic vinyl compound and a vinyl cyanide compound, and the total usage amount is determined from molding processability, chemical resistance, hydrolysis resistance, dimensional stability, From the viewpoint of molding designability and the like, it is preferably 70 to 100% by mass, more preferably 80 to 100% by mass based on the total amount of the vinyl monomer (b11). In addition, the use ratio of the aromatic vinyl compound and the vinyl cyanide compound is calculated from the viewpoints of molding processability, chemical resistance, hydrolysis resistance, dimensional stability, molding appearance, etc., when the total of these compounds is taken as 100. In the case of mass %, it is preferably 5-95 mass % and 5-95 mass %, more preferably 50-95 mass % and 5-50 mass %, and still more preferably 60-95 mass % and 5-40 mass % .

Moreover, when the said vinyl type monomer (b11) contains a maleimide type compound, heat resistance can be imparted to a 1st resin layer. The preferable content of the structural unit originating in the maleimide compound contained in the said aromatic vinyl type resin is mentioned later.

As the rubber-reinforced aromatic vinyl-based resin (I-1), preferred resins are as follows.

[1-1] A rubber-reinforced aromatic vinyl system obtained by polymerizing a vinyl monomer (b11) composed of an aromatic vinyl compound and a vinyl cyanide compound in the presence of a rubbery polymer (a11). resin

[1-2] Obtained by polymerizing a vinyl monomer (b11) composed of an aromatic vinyl compound, a vinyl cyanide compound, and a maleimide compound in the presence of a rubbery polymer (a11). Rubber-reinforced aromatic vinyl resins

[1-3] Rubber obtained by polymerizing a vinyl monomer (b11) composed of an aromatic vinyl compound, a vinyl cyanide compound, and a methacrylate compound in the presence of a rubbery polymer (a11) Reinforced aromatic vinyl resin

The aforementioned rubber-reinforced aromatic vinyl resin (I-1) can be produced by polymerizing the aforementioned vinyl monomer (b11) in the presence of the aforementioned rubbery polymer (a11). The polymerization method may be emulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization, or a polymerization method combining these polymerization methods.

It should be noted that, during the manufacture of the rubber-reinforced aromatic vinyl resin (I-1), the rubbery polymer (a11) and the above-mentioned vinyl monomer (b11) may be in the reaction system, and in the above-mentioned rubber In the presence of the total amount of the polymer (a11), the above-mentioned vinyl monomer is added at one time to initiate polymerization (b11), and the polymerization may be carried out while adding it separately or continuously. In addition, the above-mentioned vinyl-based monomer (b11) may be added at one time in the presence or absence of a part of the above-mentioned rubbery polymer (a11) to initiate polymerization, or may be added separately or continuously. At this time, the remainder of the above-mentioned rubbery polymer (a11) may be added all at once, dividedly, or continuously during the reaction.

In the case of producing the rubber-reinforced aromatic vinyl resin (I-1) by emulsion polymerization, a polymerization initiator, a chain transfer agent (molecular weight modifier), an emulsifier, water, and the like can be used.

Examples of the above-mentioned polymerization initiator include organic peroxides, sugar-containing pyrophosphate formulations, sulfoxylate formulations, etc., in which cumene hydroperoxide, dicumyl hydroperoxide, p-menthane hydroperoxide, etc. are combined. Redox initiators of reducing agents; persulfates such as potassium persulfate; benzoyl peroxide (BPO), lauroyl peroxide, tert-butyl peroxylaurate, tert-butyl peroxymonocarboxylic acid Peroxides such as esters, etc. These compounds may be used alone or in combination of two or more. Moreover, the usage-amount of the said polymerization initiator is 0.1-1.5 mass % normally with respect to the said vinylic monomer (b11) whole quantity.

It should be noted that the above-mentioned polymerization initiator may be added to the reaction system at one time or continuously.

Examples of the aforementioned chain transfer agent include octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-hexyl mercaptan, n-hexadecyl mercaptan, and n-tetradecyl mercaptan. , tertiary tetradecyl mercaptan and other mercaptans; terpinolene, dimer of α-methylstyrene, etc. These compounds may be used alone or in combination of two or more. The usage-amount of the said chain transfer agent is 0.05-2.0 mass % normally with respect to the said vinylic monomer (b11) whole quantity.

It should be noted that the above-mentioned chain transfer agent may be added to the reaction system at one time or continuously.

Anionic surfactant and nonionic surfactant are mentioned as said emulsifier. Examples of anionic surfactants include sulfuric acid esters of higher alcohols; alkylbenzenesulfonates such as sodium dodecylbenzenesulfonate; aliphatic sulfonates such as sodium lauryl sulfate; higher aliphatic carboxylic acids Salt, aliphatic phosphate, etc. Moreover, as a nonionic surfactant, the alkyl ester type compound of polyethylene glycol, an alkyl ether type compound, etc. are mentioned. These compounds may be used alone or in combination of two or more. The usage-amount of the said emulsifier is 0.3-5.0 mass % normally with respect to the said vinylic monomer (b11) whole quantity.

Emulsion polymerization can be performed under known conditions depending on the types of vinyl monomer (b11), polymerization initiator, and the like. The latex obtained by the emulsion polymerization is usually purified by coagulating with a coagulant to make the polymer component powdery, followed by washing with water and drying. As the coagulant, inorganic salts such as calcium chloride, magnesium sulfate, magnesium chloride, and sodium chloride; inorganic acids such as sulfuric acid and hydrochloric acid; organic acids such as acetic acid and lactic acid, and the like can be used.

In addition, when two or more types of rubber-reinforced aromatic vinyl-based resins (I-1) are contained in the above-mentioned aromatic vinyl-based resins, the resins may be separated from each latex and then mixed, but as As another method, there is a method of coagulating a mixture of latexes containing respective resins.

As a method for producing the rubber-reinforced aromatic vinyl resin (I-1) obtained by solution polymerization, bulk polymerization, and bulk-suspension polymerization, known methods can be used.

It should be noted that, as the above rubber-reinforced aromatic vinyl resin (I-1), there can be used compounds having butadiene rubber-reinforced aromatic vinyl-based resin, acrylic rubber-reinforced aromatic vinyl-based resin, silicone rubber Commercially available products made of reinforced styrene resin, silicone-acrylic composite rubber reinforced styrene resin, etc. For example, a rubber-reinforced aromatic vinyl resin using silicone-acrylic composite rubber as the rubbery polymer (a11) is a commercially available product obtained by the method described in JP-A-4-239010, for example, "Metaburen SX-006" (trade name) manufactured by Mitsubishi Rayon Co., Ltd., etc. are mentioned.

The graft ratio of the rubber-reinforced aromatic vinyl resin (I-1) is preferably 20 to 170%, more preferably 30 to 170%, and still more preferably 40 to 150%. When the graft ratio is too low, the flexibility of the first resin layer may be insufficient. On the other hand, when the graft ratio is too high, the viscosity of the first thermoplastic resin composition may become high, and thinning may become difficult.

The above-mentioned graft ratio can be obtained by the following formula.

Grafting rate (%)={(S-T)/T}×100

In the above formula, S is the temperature at 25°C when 1 g of the rubber-reinforced aromatic vinyl resin (I-1) is put into 20 ml of acetone (when the rubbery polymer (a11) is an acrylic rubber, acetonitrile). The mass of the insoluble component obtained by separating the insoluble component from the soluble component after being vibrated by a vibrator for 2 hours at a temperature of 5°C for 60 minutes with a centrifuge (number of revolutions; 23,000 rpm) ( g), T is the mass (g) of the rubbery polymer (a11) contained in 1 gram of the rubber-reinforced aromatic vinyl-based resin (I-1). The mass of the rubbery polymer (a11) can be obtained by a method of calculating from a polymerization recipe and a polymerization conversion rate, a method of calculating from an infrared absorption spectrum (IR), or the like.

The aforementioned rubber-reinforced aromatic vinyl resin (I-1) may be used alone or in combination of two or more.

As described above, the aromatic vinyl resin can be obtained by polymerizing a rubber-reinforced aromatic vinyl resin (I-1) and a vinyl monomer (b12) containing an aromatic vinyl compound (co- ) a mixture of polymers (I-2). In this case, the above-mentioned (co)polymer (I-2) may be either a homopolymer or a copolymer, or may be a combination thereof.

The above-mentioned vinyl monomer (b12) may be an aromatic vinyl compound alone, or may be a combination of the aromatic vinyl compound and other monomers. Examples of other monomers include vinyl cyanide compounds, (meth)acrylate compounds, maleimide-based compounds, unsaturated acid anhydrides, carboxyl-containing unsaturated compounds, hydroxyl-containing unsaturated compounds, ring-containing Oxygen unsaturated compounds, oxazoline group-containing unsaturated compounds, etc. These compounds may be used alone or in combination of two or more. As each of the above-mentioned compounds, the compounds exemplified for the above-mentioned vinyl monomer (b11) can be used.

The aforementioned (co)polymer (I-2) is preferably a copolymer. In the present invention, the above-mentioned vinyl monomer (b12) is preferably composed of an aromatic vinyl compound and other monomers. Other monomers are preferably vinyl cyanide compounds and maleimide compounds.

When the vinyl monomer (b12) contains an aromatic vinyl compound and a vinyl cyanide compound, the total amount of these compounds is preferably 40 to 100 mass by mass relative to the entire vinyl monomer (b12). %, more preferably 50 to 100% by mass. In addition, the use ratio of the aromatic vinyl compound and the cyanide vinyl compound is considered as the total of these compounds from the viewpoints of moldability, chemical resistance, hydrolysis resistance, dimensional stability, molding appearance, etc. In the case of 100% by mass, it is preferably 5 to 95% by mass and 5 to 95% by mass, more preferably 40 to 95% by mass and 5 to 60% by mass, further preferably 50 to 90% by mass and 10 to 50% by mass %.

When the above (co)polymer (I-2) is a copolymer, preferred polymers are as follows.

[1-4] A structural unit derived from an aromatic vinyl compound (hereinafter referred to as "structural unit (s)") and a structural unit derived from a cyanide vinyl compound (hereinafter referred to as "structural unit (t)"). ) composed of copolymers

[1-5] A structural unit (s) derived from an aromatic vinyl compound, a structural unit (t) derived from a vinyl cyanide compound, and a structural unit derived from a maleimide compound (hereinafter referred to as "structural unit") Unit (u)".) Copolymers composed of

The above-mentioned (co)polymer (I-2), in the case of the above-mentioned embodiment [1-4], the content ratio of the structural unit (s) and the structural unit (t) can be determined from moldability, chemical resistance, and water resistance. From the standpoints of degradability, dimensional stability, molding appearance, etc., when the total of them is taken as 100% by mass, it is preferably 5 to 95% by mass and 5 to 95% by mass, and more preferably 40 to 95% by mass. And 5-60 mass %, More preferably, it is 50-90 mass % and 10-50 mass %.

Examples of the copolymer of the above aspect [1-4] include acrylonitrile/styrene copolymers, acrylonitrile/α-methylstyrene copolymers, and the like.

In the case of the above-mentioned (co)polymer (I-2) in the above-mentioned form [1-5], the content ratio of the structural unit (s), the structural unit (t) and the structural unit (u) is determined from moldability, durability, From the viewpoint of heat resistance, chemical resistance, hydrolysis resistance, dimensional stability, flexibility, etc., when the total of them is taken as 100% by mass, it is preferably 20 to 90% by mass, 5 to 50% by mass, and 1% by mass, respectively. to 40% by mass, more preferably 25 to 85% by mass, 10 to 45% by mass and 5 to 35% by mass, further preferably 30 to 80% by mass, 10 to 40% by mass and 10 to 30% by mass.

Examples of the above aspect [1-5] include acrylonitrile-styrene-N-phenylmaleimide copolymers and the like.

In addition, as the above-mentioned (co)polymer (I-2), an acrylonitrile·styrene·methacrylic acid methyl copolymer or the like can be used.

The above (co)polymer (I-2) can be produced by polymerizing an aromatic vinyl compound-containing vinyl monomer (b12) in the presence or absence of a polymerization initiator. As a polymerization method, when a polymerization initiator is used, solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, etc. are preferable, and these polymerization methods may be used in combination. In addition, thermal polymerization may be employed without using a polymerization initiator.

As the polymerization initiator, the compounds exemplified in the description of the method for producing the rubber-reinforced aromatic vinyl resin (I-1) may be used alone or in combination of two or more. The usage-amount of the said polymerization initiator is 0.1-1.5 mass % normally with respect to the said vinylic monomer (b12) whole quantity.

In addition, the chain transfer agent, emulsifier etc. which can be used at the time of manufacture of the said rubber-reinforced aromatic vinyl resin (I-1) can be used as needed.

In the production of the above-mentioned (co)polymer (I-2), the polymerization may be initiated with the total amount of the vinyl monomer (b12) accommodated in the reaction system, or an arbitrarily selected monomer may be added separately or continuously. Body components are aggregated. Furthermore, when using the said polymerization initiator, it can add to a reaction system once or continuously.

The above (co)polymers (I-2) may be used alone or in combination of two or more.

In addition, when the above-mentioned aromatic vinyl-based resin is a (co)polymer (I-2), the above-mentioned (co)polymer (I-2) can be used as it is.

In the case where the above-mentioned aromatic vinyl resin is composed of rubber-reinforced aromatic vinyl resin (I-1), and the rubber-reinforced aromatic vinyl resin (I-1) and (co)polymer (I- 2) In either case of the mixture configuration, the intrinsic viscosity of the component soluble in acetone (among them, acetonitrile when the rubbery polymer is acrylic rubber) of the aromatic vinyl resin is [ η] (in methyl ethyl ketone, measured at 30°C) is preferably 0.1 to 2.5 dl/g, more preferably 0.2 to 1.5 dl/g, even more preferably 0.25 to 1.2 dl/g. When the intrinsic viscosity [η] is within the above range, the moldability of the first thermoplastic resin composition is excellent, and the thickness accuracy of the first resin layer is also excellent.

Here, the intrinsic viscosity [η] can be obtained as follows.

When obtaining the graft ratio in the above-mentioned aromatic vinyl-based resin (including the rubber-reinforced aromatic vinyl-based resin (I-1)), the acetone-soluble component recovered after centrifugation (in the rubber-like polymer is In the case of acrylic rubber, acetonitrile soluble content) was dissolved in methyl ethyl ketone to prepare 5 solutions with different concentrations, and the reduced viscosity of each concentration was measured at 30°C using an Ubbelohde viscosity tube to obtain the intrinsic viscosity [η].

The above-mentioned graft ratio and intrinsic viscosity [η] can be adjusted by adjusting the polymerization initiator, chain viscosity and The types and amounts of transfer agents, emulsifiers, solvents, etc., and further, polymerization time, polymerization temperature, etc. can be easily controlled.

In addition, the intrinsic viscosity [η] of the above-mentioned aromatic vinyl resin can be appropriately selected from rubber-reinforced aromatic vinyl resin (I-1) and (co)polymer (I- 2) to adjust.

When imparting sufficient heat resistance to the above-mentioned first resin layer, the above-mentioned aromatic vinyl-based resin preferably contains a structural unit (u) derived from a maleimide-based compound. The structural unit (u) may be a structural unit derived from the rubber-reinforced aromatic vinyl resin (I-1) or a structural unit derived from the (co)polymer (I-2). In addition, it may be a structural unit derived from both.

The content of the structural unit (u) for forming the first resin layer excellent in heat resistance is preferably 1 to 40 mass %, more preferably 3 to 40 mass %, based on 100 mass % of the above-mentioned thermoplastic resin (I). 35% by mass, more preferably 5 to 30% by mass. When the content of the structural unit (u) is within the above range, it is possible to form a solar cell back sheet excellent in balance between heat resistance and flexibility. Especially in the case of manufacturing a solar cell module, there is no inconvenience in handling the back sheet for solar cells, and when bonding the front side transparent protective member, the front side sealing film, the solar cell element, the back side sealing film, and the back sheet, even Heating at a temperature of 100° C. or higher can also be used for pressure-compression bonding without deformation. In addition, when the content of the structural unit (u) contained in the said thermoplastic resin (I) is too much, the flexibility of a 1st resin layer may fall.

The above-mentioned first resin layer is an infrared-transmitting colored resin layer, and preferably has a property of absorbing visible rays and transmitting infrared rays. Furthermore, the first thermoplastic resin composition forming the first resin layer is preferably a composition containing an infrared-transmitting colorant.

The above-mentioned infrared-transmitting coloring agent is usually colored other than white, and is preferably a dark color such as black, brown, dark blue, or dark green. By using a dark-colored infrared-transmitting colorant, it is possible to provide a solar cell module having an excellent dark-colored appearance without impairing the adhesiveness between the first resin layer and the filler portion in which the solar cell element is embedded.

Perylene-based pigments etc. are mentioned as said infrared transmissive coloring agent. As the perylene-based pigment, compounds represented by the following general formulas (2) to (4) and the like can be used.

[chemical 1]

(In the formula, R ² and R ³ are the same or different, and are butyl, phenylethyl, methoxyethyl or 4-methoxyphenylmethyl.)

[Chem 2]

(wherein, R ⁴ and R ⁵ are the same or different, and are phenylene, 3-methoxyphenylene, 4-methoxyphenylene, 4-ethoxyphenylene, carbon number 1-3 Alkylphenylene, hydroxyphenylene, 4,6-dimethylphenylene, 3,5-dimethylphenylene, 3-chlorophenylene, 4-chlorophenylene, 5- Chlorophenylene, 3-bromophenylene, 4-bromophenylene, 5-bromophenylene, 3-fluorophenylene, 4-fluorophenylene, 5-fluorophenylene, naphthylene , naphthalenediyl, pyridylidene, 2,3-pyridinediyl, 3,4-pyridinediyl, 4-methyl-2,3-pyridinediyl, 5-methyl-2,3-pyridinediyl , 6-methyl-2,3-pyridinediyl, 5-methyl-3,4-pyridinediyl, 4-methoxy-2,3-pyridinediyl or 4-chloro-2,3-pyridine Two bases.)

[Chem 3]

(wherein, R ⁶ and R ⁷ are the same or different, and are phenylene, 3-methoxyphenylene, 4-methoxyphenylene, 4-ethoxyphenylene, carbon number 1-3 Alkylphenylene, hydroxyphenylene, 4,6-dimethylphenylene, 3,5-dimethylphenylene, 3-chlorophenylene, 4-chlorophenylene, 5- Chlorophenylene, 3-bromophenylene, 4-bromophenylene, 5-bromophenylene, 3-fluorophenylene, 4-fluorophenylene, 5-fluorophenylene, naphthylene , naphthalenediyl, pyridylidene, 2,3-pyridinediyl, 3,4-pyridinediyl, 4-methyl-2,3-pyridinediyl, 5-methyl-2,3-pyridinediyl , 6-methyl-2,3-pyridinediyl, 5-methyl-3,4-pyridinediyl, 4-methoxy-2,3-pyridinediyl or 4-chloro-2,3-pyridine Two bases.)

In addition, as the above-mentioned perylene-based pigments, commercially available products such as "Paliogen Black S0084", "Paliogen Black L 0086", "Lumogen Black FK4280", "Lumogen Black FK4281" (all of which are trade names manufactured by BASF Corporation) can be used. sale.

The above-mentioned infrared transmissive colorants may be used alone or in combination of two or more.

The content ratio of the infrared transparent coloring agent in the above-mentioned first thermoplastic resin composition is preferably 5 with respect to 100 parts by mass of the above-mentioned thermoplastic resin (I) from the viewpoint of the above-mentioned transmittance and absorptivity to each light. The content is at most parts by mass, more preferably 0.1 to 5 parts by mass.

In addition, in the back sheet for solar cells of this invention, other coloring agents can be used according to the purpose, application, etc. as long as the infrared transmittance is not reduced. For example, yellow pigments, cyan pigments, and the like can be used as colorants other than infrared-transmitting colorants, and solar cell modules having various appearances can be formed by combinations as described below.

[1] Brown coloring obtained by combining a black-based infrared-transmitting colorant and a yellow-based pigment

[2] Deep cyan coloring obtained by combining a black-based infrared-transmitting colorant and a cyan-based pigment

When other colorants are used, the proportion in the first thermoplastic resin composition is usually 60 parts by mass or less, preferably 0.01 to 55 parts by mass, based on 100 parts by mass of the infrared transparent colorant.

It should be noted that the first thermoplastic resin composition forming the above-mentioned first resin layer preferably does not substantially contain a white coloring agent, and when the white coloring agent is contained, the upper limit of the content is equal to (I) 100 parts by mass, usually 3 parts by mass, preferably 1 part by mass.

The degree of coloring of the first resin layer is not particularly limited as long as it satisfies the infrared transmittance of the first resin layer, and the L value of the coloring reaching the surface on the side of the first resin layer in the solar battery back sheet is preferably 40. or less, more preferably 35 or less, even more preferably 30 or less.

In addition, carbon black is known as a dark-color coloring agent. Since the carbon black absorbs light having a wavelength in the infrared region, when sunlight leaks from the gap between adjacent solar cell elements onto the first resin layer containing carbon black, the first resin layer stores heat. In addition, the temperature of the filling material portion including the solar cell element may be increased by the first resin layer that has stored heat, thereby lowering the power generation efficiency in some cases. In the present invention, the above-mentioned first resin layer contains an infrared-transmissive coloring agent, thereby being excellent in designability and durability without lowering power generation efficiency.

The above-mentioned first thermoplastic resin composition may contain additives depending on the purpose, use, and the like. Examples of such additives include antioxidants, ultraviolet absorbers, antiaging agents, plasticizers, fluorescent whitening agents, weather resistance agents, fillers, antistatic agents, flame retardants, antifogging agents, antibacterial agents, antifungal agents, and antifungal agents. agent, antifouling agent, tackifier, silane coupling agent, etc. The specific compounds and their compounding amounts among these additives will be described later.

In order to form the first thermoplastic resin composition containing the above-mentioned additives, a melt-kneading method is generally used. As an apparatus used for melt-kneading, a single-screw extruder, a twin-screw extruder, a Banbury mixer, a kneader, a continuous kneader, etc. are mentioned.

The thickness of the first resin layer is usually 5 to 500 μm, preferably 8 to 400 μm.

The thermoplastic resin (II) contained in the second thermoplastic resin composition forming the second resin layer (white resin layer) is not particularly limited as long as it has thermoplasticity. Examples of the thermoplastic resin (II) constituting the second resin layer include aromatic vinyl resins, polyolefin resins, polyvinyl chloride resins, polyvinylidene chloride resins, polyvinyl acetate resins, saturated polyester resins, Polycarbonate resin, acrylic resin, fluororesin, ethylene-vinyl acetate resin, etc. These resins may be used alone or in combination of two or more to form an alloy. In addition, among the above-mentioned resins, aromatic vinyl-based resins are preferable from the viewpoint of hydrolysis resistance and dimensional stability.

The above-mentioned thermoplastic resin (II) may be the same as or different from the above-mentioned thermoplastic resin (I).

The above-mentioned aromatic vinyl-based resin is a rubber-reinforced aromatic vinyl-based resin obtained by polymerizing an aromatic vinyl compound or the like in the presence of a rubbery polymer as described above; vinyl containing an aromatic vinyl compound is used. (Co) polymers made of monomers, etc. In the present invention, the above-mentioned aromatic vinyl resin is preferably a rubber-reinforced aromatic vinyl resin. The above-mentioned thermoplastic resin (II) contains a rubber-reinforced aromatic vinyl resin, thereby forming a second resin layer excellent in hydrolysis resistance, dimensional stability, and impact resistance.

Examples of the above-mentioned aromatic vinyl-based resins include rubber-reinforced aromatic vinyl resins obtained by polymerizing a vinyl-based monomer (b21) containing an aromatic vinyl compound in the presence of a rubbery polymer (a21). resin (II-1), a (co)polymer (II-2) of a vinyl monomer (b22) containing an aromatic vinyl compound, and a rubber-reinforced aromatic vinyl resin (II-1) and Mixture of (co)polymers (II-2).

The above-mentioned aromatic vinyl-based resin preferably contains at least one rubber-reinforced aromatic vinyl-based resin (II-1) as described above, and a rubber-reinforced aromatic vinyl-based resin is particularly preferable from the viewpoint of impact resistance and flexibility. A combination of one or more types of resin (II-1) and one or more types of (co)polymers (II-2) described above. In this case, the content of the rubbery polymer (a21) in the aromatic vinyl resin is preferably 5 to 40% by mass, More preferably, it is 8-30 mass %, More preferably, it is 10-20 mass %, Especially preferably, it is 12-18 mass %. When the said content exceeds 40 mass %, heat resistance may become inadequate, and formation of the 2nd resin layer using a 2nd thermoplastic resin composition may become difficult. On the other hand, when the said content is less than 5 mass %, flexibility may become insufficient.

As the rubber-like polymer (a21) that can be used for forming the rubber-reinforced aromatic vinyl-based resin (II-1) above, rubber-reinforced aromatic vinyl polymers contained in the first thermoplastic resin composition can be used. The polymer is exemplified as the rubbery polymer (a11) used for forming the resin (I-1). The rubbery polymer (a21) is preferably acrylic rubber, ethylene-α-olefin rubber, hydrogenated conjugated diene rubber, silicone rubber, and silicone-acrylic composite rubber from the viewpoint of weather resistance. From the viewpoint of impact resistance, a conjugated diene rubber is preferable.

The shape and volume average particle diameter of the above-mentioned rubbery polymer (a21) may be the same as those described for the above-mentioned rubbery polymer (a11).

The type, shape, and volume average particle diameter of the above-mentioned rubbery polymer (a21) may be the same as or different from those of the above-mentioned rubbery polymer (a11).

As the vinyl monomer (b21) used for forming the above-mentioned rubber-reinforced aromatic vinyl-based resin (II-1), the rubber-reinforced aromatic vinyl-based monomer contained in the above-mentioned first thermoplastic resin composition can be used. Compounds exemplified as the vinyl monomer (b11) used in the formation of the resin (I-1). Preferred vinyl monomers (b21) are aromatic vinyl compounds and vinyl cyanide compounds. As aromatic vinyl compounds, styrene and α-methylstyrene are preferred. As vinyl cyanide compounds, preferred Acrylonitrile.

The above-mentioned vinyl monomer (b21) may be the same as or different from the above-mentioned vinyl monomer (b11).

The total usage amount of the aromatic vinyl compound and the vinyl cyanide compound in the above-mentioned vinyl monomer (b21) is determined from the viewpoints of molding processability, chemical resistance, hydrolysis resistance, dimensional stability, molding appearance, etc. It is considered that it is preferably 70 to 100% by mass, more preferably 80 to 100% by mass based on the total amount of the vinyl monomer (b21). In addition, the use ratio of the aromatic vinyl compound and the vinyl cyanide compound is calculated from the viewpoints of molding processability, chemical resistance, hydrolysis resistance, dimensional stability, molding appearance, etc., when the total of them is taken as 100 mass %, respectively, preferably 5 to 95% by mass and 5 to 95% by mass, more preferably 50 to 95% by mass and 5 to 50% by mass, further preferably 60 to 90% by mass and 10 to 40% by mass.

Moreover, when the said vinyl type monomer (b21) contains a maleimide type compound, heat resistance can be imparted to a 2nd resin layer. The preferable content of the structural unit originating in the maleimide compound contained in the said aromatic vinyl type resin is mentioned later.

As the rubber-reinforced aromatic vinyl-based resin (II-1), preferred resins are as follows.

[2-1] A rubber-reinforced aromatic vinyl system obtained by polymerizing a vinyl monomer (b21) composed of an aromatic vinyl compound and a vinyl cyanide compound in the presence of a rubbery polymer (a21). resin

[2-2] Obtained by polymerizing a vinyl monomer (b21) composed of an aromatic vinyl compound, a vinyl cyanide compound, and a maleimide compound in the presence of a rubbery polymer (a21). Rubber-reinforced aromatic vinyl resins

[2-3] Rubber obtained by polymerizing a vinyl monomer (b21) composed of an aromatic vinyl compound, a vinyl cyanide compound, and a methacrylate compound in the presence of a rubbery polymer (a21) Reinforced aromatic vinyl resin

The method for producing the rubber-reinforced aromatic vinyl resin (II-1) is the same as the method for producing the rubber-reinforced aromatic vinyl resin (I-1).

The graft ratio of the rubber-reinforced aromatic vinyl resin (II-1) is preferably 20 to 170%, more preferably 30 to 170%, and still more preferably 40 to 150%. When the graft ratio is too low, the flexibility of the second resin layer may be insufficient. On the other hand, when the graft ratio is too high, the viscosity of the second thermoplastic resin composition may become high, and thickness reduction may become difficult.

The aforementioned rubber-reinforced aromatic vinyl resin (II-1) may be used alone or in combination of two or more.

As described above, preferred aromatic vinyl resins are those obtained by polymerizing a rubber-reinforced aromatic vinyl resin (II-1) and a vinyl monomer (b22) containing an aromatic vinyl compound ( Co) mixtures of polymers (II-2). In this case, the above-mentioned (co)polymer (II-2) may be either a homopolymer or a copolymer, or may be a combination of both.

The above-mentioned vinyl monomer (b22) may be an aromatic vinyl compound alone, or may be a combination of the aromatic vinyl compound and other monomers. Examples of other monomers include vinyl cyanide compounds, (meth)acrylate compounds, maleimide-based compounds, unsaturated acid anhydrides, carboxyl-containing unsaturated compounds, hydroxyl-containing unsaturated compounds, ring-containing Oxygen unsaturated compounds, oxazoline group-containing unsaturated compounds, etc. These compounds may be used alone or in combination of two or more. As each of the above-mentioned compounds, the compounds exemplified for the above-mentioned vinyl monomer (b11) can be used.

The above-mentioned vinyl monomer (b22) may be the same as the vinyl monomer (b12) used in the formation of the (co)polymer (I-2) contained in the above-mentioned first thermoplastic resin composition, or Can be different.

The aforementioned (co)polymer (II-2) is preferably a copolymer. In the present invention, the above-mentioned vinyl monomer (b22) is preferably composed of an aromatic vinyl compound and other monomers. Other monomers are preferably vinyl cyanide compounds and maleimide compounds.

When the above-mentioned vinyl-based monomer (b22) contains an aromatic vinyl compound and a vinyl cyanide compound, the total amount thereof is preferably 40 to 100 mass by mass relative to the entirety of the above-mentioned vinyl-based monomer (b22) %, more preferably 50 to 100% by mass. In addition, the use ratio of the aromatic vinyl compound and the vinyl cyanide compound is considered from the viewpoints of molding processability, chemical resistance, hydrolysis resistance, dimensional stability, molding appearance, etc., when the total of them is taken as 100. In the case of mass %, it is preferably 5-95 mass % and 5-95 mass %, more preferably 40-95 mass % and 5-60 mass %, and still more preferably 50-90 mass % and 10-50 mass % .

When the above (co)polymer (II-2) is a copolymer, preferred polymers are as follows.

[2-4] Copolymer composed of a structural unit (s) derived from an aromatic vinyl compound and a structural unit (t) derived from a cyanide vinyl compound

[2-5] Copolymerization consisting of a structural unit (s) derived from an aromatic vinyl compound, a structural unit (t) derived from a vinyl cyanide compound, and a structural unit (u) derived from a maleimide compound thing

The production method of the above-mentioned (co)polymer (II-2) is the same as the production method of the above-mentioned (co)polymer (I-2).

The above (co)polymers (II-2) may be used alone or in combination of two or more.

In addition, when the said aromatic vinyl-type resin is a (co)polymer (II-2), the (co)polymer (II-2) described above can be used as it is.

In the case where the above aromatic vinyl resin is composed of rubber-reinforced aromatic vinyl resin (II-1), and when the rubber-reinforced aromatic vinyl resin (II-1) and (co)polymer (II- In either case of the mixture configuration of 2), the intrinsic viscosity [η ] (in methyl ethyl ketone, measured at 30°C) is preferably 0.1 to 2.5 dl/g, more preferably 0.2 to 1.5 dl/g, even more preferably 0.25 to 1.2 dl/g. When the intrinsic viscosity [η] is within the above range, the moldability of the second thermoplastic resin composition is excellent, and the thickness accuracy of the second resin layer is also excellent.

When imparting sufficient heat resistance to the above-mentioned second resin layer, the above-mentioned aromatic vinyl-based resin preferably contains a structural unit (u) derived from a maleimide-based compound. The structural unit (u) may be a structural unit derived from the rubber-reinforced aromatic vinyl resin (II-1) or a structural unit derived from the (co)polymer (II-2). In addition, it may be a structural unit derived from both.

The content of the structural unit (u) for forming the second resin layer excellent in heat resistance is preferably 1 to 50 mass %, more preferably 5 to 5 mass %, based on 100 mass % of the above thermoplastic resin (II). 45% by mass, more preferably 10 to 40% by mass. When the content of the structural unit (u) is within the above range, a back sheet for a solar cell having an excellent balance between heat resistance and flexibility can be formed. Especially in the case of manufacturing solar cell modules, there is no inconvenience in handling the back sheet for solar cells. Even heating at a temperature of 100° C. or higher allows pressure bonding without deformation. In addition, when there is too much content of the structural unit (u) contained in the said thermoplastic resin (II), the flexibility of a 2nd resin layer may fall.

The above-mentioned second resin layer is a white resin layer, and preferably has a property of reflecting visible light and infrared light. Moreover, it is preferable that the 2nd thermoplastic resin composition which forms this 2nd resin layer is a composition containing a white coloring agent.

Examples of the above-mentioned white coloring agent include titanium oxide, zinc oxide, calcium carbonate, barium sulfate, calcium sulfate, aluminum oxide, silicon dioxide, 2PbCO ₃ ·Pb(OH) ₂ , [ZnS+BaSO ₄ ], talc, Gypsum etc. These substances may be used alone or in combination of two or more.

The content of the above-mentioned white-based coloring agent is, in particular, when light having a wavelength of 800 to 1,400 nm is radiated from the surface of the first resin layer in the back sheet for solar cells, the amount of light on the surface of the above-mentioned first resin layer is From the viewpoint of light reflectivity, 1-45 mass parts is preferable with respect to 100 mass parts of said thermoplastic resins (II), More preferably, it is 3-40 mass parts, More preferably, it is 5-30 mass parts. When there is too much content of this white coloring agent, the flexibility of the back sheet for solar cells of this invention may fall.

The above-mentioned second resin layer (white resin layer) is preferably a layer having an L value (brightness) of 60 or more on the surface of a film composed of a single layer thereof, more preferably the L value is 65 or more, and even more preferably 70 or more.

It should be noted that, as long as light with a wavelength of 800 to 1,400 nm is radiated to the surface of the first resin layer in the back sheet for solar cells, the reflectance of the light on the surface of the first resin layer is not reduced. The above-mentioned second thermoplastic resin composition may contain other colorants (for example, yellow-based colorants, cyan-based colorants, etc.) depending on the purpose, application, etc. When using another coloring agent, the content is usually 10 parts by mass or less with respect to 100 parts by mass of the above-mentioned thermoplastic resin (II).

The above-mentioned second thermoplastic resin composition may contain additives depending on the purpose, use, and the like. Examples of such additives include antioxidants, ultraviolet absorbers, antiaging agents, plasticizers, fluorescent whitening agents, weather resistance agents, fillers, antistatic agents, flame retardants, antifogging agents, antibacterial agents, antifungal agents, and antifungal agents. agent, antifouling agent, tackifier, silane coupling agent, etc. The specific compounds and their compounding amounts among these additives will be described later.

The thickness of the second resin layer is usually 10 to 990 μm, preferably 20 to 500 μm.

The thermoplastic resin (III) contained in the third thermoplastic resin composition forming the third resin layer is not particularly limited as long as it is a thermoplastic resin. Examples of the thermoplastic resin (III) constituting the third resin layer include aromatic vinyl resins, polyolefin resins, polyvinyl chloride resins, polyvinylidene chloride resins, polyvinyl acetate resins, saturated polyester resins, Polycarbonate resin, acrylic resin, fluororesin, ethylene-vinyl acetate resin, etc. These resins may be used alone or in combination of two or more. In addition, among the above-mentioned resins, aromatic vinyl-based resins are preferable from the viewpoint of hydrolysis resistance and dimensional stability.

The aforementioned thermoplastic resin (III) may be the same as or different from the aforementioned thermoplastic resin (I). In addition, the above-mentioned thermoplastic resin (III) may be the same as or different from the above-mentioned thermoplastic resin (II).

The above-mentioned aromatic vinyl resin is, as mentioned above, a rubber-reinforced aromatic vinyl resin obtained by polymerizing an aromatic vinyl compound or the like in the presence of a rubbery polymer; (Co)polymers made of vinyl monomers, etc. In the present invention, the above-mentioned aromatic vinyl resin is preferably a rubber-reinforced aromatic vinyl resin. When the thermoplastic resin (III) contains a rubber-reinforced aromatic vinyl resin, it is possible to form a third resin layer excellent in hydrolysis resistance, dimensional stability, and impact resistance.

Examples of the aforementioned aromatic vinyl resins include rubber-reinforced aromatic vinyl resins obtained by polymerizing a vinyl monomer (b31) containing an aromatic vinyl compound in the presence of a rubbery polymer (a31). resin (III-1), a (co)polymer (III-2) of a vinyl monomer (b32) containing an aromatic vinyl compound, and a rubber-reinforced aromatic vinyl resin (III-1) and Mixture of (co)polymers (III-2).

The aromatic vinyl resin described above preferably contains at least one rubber-reinforced aromatic vinyl resin (III-1), particularly preferably one or more rubber-reinforced aromatic vinyl resins (III-1). , or a combination of one or more rubber-reinforced aromatic vinyl resins (III-1) and one or more of the aforementioned (co)polymers (III-2). In these cases, the content of the rubbery polymer (a31) in the aromatic vinyl resin is preferably 5 to 40% by mass relative to 100% by mass of the thermoplastic resin (III) containing the aromatic vinyl resin, More preferably, it is 8-30 mass %, More preferably, it is 10-20 mass %, Especially preferably, it is 12-18 mass %. When the said content exceeds 40 mass %, heat resistance may become inadequate, and formation of the 3rd resin layer using a 3rd thermoplastic resin composition may become difficult. On the other hand, when the said content is less than 5 mass %, flexibility may become insufficient.

As the rubber-like polymer (a31) used in the formation of the above-mentioned rubber-reinforced aromatic vinyl resin (III-1), the rubber-reinforced aromatic vinyl polymer contained in the above-mentioned first thermoplastic resin composition can be used. Polymers exemplified as the rubbery polymer (a11) used for forming the resin (I-1). The rubbery polymer (a31) is preferably acrylic rubber, ethylene-α-olefin rubber, hydrogenated conjugated diene rubber, silicone rubber, and silicone-acrylic composite rubber from the viewpoint of weather resistance. From the viewpoint of impact resistance, conjugated diene rubber is preferable.

The shape and volume average particle diameter of the above-mentioned rubbery polymer (a31) may be the same as those described for the above-mentioned rubbery polymer (a11).

The type, shape, and volume average particle diameter of the above-mentioned rubbery polymer (a31) may be the same as or different from those of the above-mentioned rubbery polymer (a11). In addition, the type, shape, and volume average particle diameter of the aforementioned rubbery polymer (a31) may be the same as or different from those of the aforementioned rubbery polymer (a21).

As the vinyl monomer (b31) used in the formation of the above-mentioned rubber-reinforced aromatic vinyl-based resin (III-1), the rubber-reinforced aromatic vinyl contained in the above-mentioned first thermoplastic resin composition can be used. Compounds are exemplified as the vinyl monomer (b11) used for formation of the base resin (I-1). Preferred vinyl-based monomers (b31) are aromatic vinyl compounds and vinyl cyanide compounds. As aromatic vinyl compounds, styrene and α-methylstyrene are preferred. As vinyl cyanide compounds, propylene is preferred. Nitrile.

The above-mentioned vinyl monomer (b31) may be the same as or different from the above-mentioned vinyl monomer (b11). In addition, the above-mentioned vinyl-based monomer (b31) may be the same as or different from the above-mentioned vinyl-based monomer (b21).

In the above-mentioned vinyl monomer (b31), the total usage amount of the aromatic vinyl compound and the vinyl cyanide compound is determined in terms of molding processability, chemical resistance, hydrolysis resistance, dimensional stability, molding appearance, etc. From a viewpoint, it is preferable that it is 70-100 mass % with respect to a vinylic monomer (b31) whole quantity, and it is more preferable that it is 80-100 mass %. In addition, the use ratio of the aromatic vinyl compound and the vinyl cyanide compound is considered from the viewpoints of molding processability, chemical resistance, hydrolysis resistance, dimensional stability, molding appearance, etc., when the total of them is taken as 100. In the case of mass %, it is preferably 5-95 mass % and 5-95 mass %, more preferably 50-95 mass % and 5-50 mass %, and still more preferably 60-90 mass % and 10-40 mass % .

Moreover, when the said vinyl type monomer (b31) contains a maleimide type compound, heat resistance can be imparted to a 3rd resin layer. The preferable content of the structural unit originating in the maleimide compound contained in the said aromatic vinyl type resin is mentioned later.

As the rubber-reinforced aromatic vinyl-based resin (III-1), preferred resins are as follows.

[3-1] A rubber-reinforced aromatic vinyl compound obtained by polymerizing a vinyl monomer (b31) composed of an aromatic vinyl compound and a vinyl cyanide compound in the presence of a rubbery polymer (a31). resin

[3-2] Obtained by polymerizing a vinyl monomer (b31) composed of an aromatic vinyl compound, a vinyl cyanide compound, and a maleimide compound in the presence of a rubbery polymer (a31). Rubber-reinforced aromatic vinyl resins

[3-3] Rubber obtained by polymerizing a vinyl monomer (b31) composed of an aromatic vinyl compound, a vinyl cyanide compound, and a methacrylate compound in the presence of a rubbery polymer (a31) Reinforced aromatic vinyl resin

The method for producing the rubber-reinforced aromatic vinyl resin (III-1) is the same as the method for producing the rubber-reinforced aromatic vinyl resin (I-1).

The graft ratio of the rubber-reinforced aromatic vinyl resin (III-1) is preferably 20 to 170%, more preferably 30 to 170%, and still more preferably 40 to 150%. When the graft ratio is too low, the flexibility of the third resin layer may be insufficient. On the other hand, when the graft ratio is too high, the viscosity of the third thermoplastic resin composition may become high, and thickness reduction may become difficult.

The aforementioned rubber-reinforced aromatic vinyl resin (III-1) may be used alone or in combination of two or more.

As described above, preferable aromatic vinyl resins are those obtained by polymerizing a rubber-reinforced aromatic vinyl resin (III-1) and a vinyl monomer (b32) containing an aromatic vinyl compound ( Co) mixtures of polymers (III-2). In this case, the above-mentioned (co)polymer (III-2) may be either a homopolymer or a copolymer, or may be a combination of both.

The above-mentioned vinyl monomer (b32) may be an aromatic vinyl compound alone, or may be a combination of the aromatic vinyl compound and other monomers. Examples of other monomers include vinyl cyanide compounds, (meth)acrylate compounds, maleimide-based compounds, unsaturated acid anhydrides, carboxyl-containing unsaturated compounds, hydroxyl-containing unsaturated compounds, ring-containing Oxygen unsaturated compounds, oxazoline group-containing unsaturated compounds, etc. These compounds may be used alone or in combination of two or more. As each of the above-mentioned compounds, the compounds exemplified for the above-mentioned vinyl monomer (b11) can be used.

The above-mentioned vinyl monomer (b32) may be the same as the vinyl monomer (b12) used in the formation of the (co)polymer (I-2) contained in the above-mentioned first thermoplastic resin composition, or may be different. In addition, the above-mentioned vinyl-based monomer (b32) may be the same as the vinyl-based monomer (b22) used for forming the (co)polymer (II-2) contained in the above-mentioned second thermoplastic resin composition, It can also be different.

The aforementioned (co)polymer (III-2) is preferably a copolymer. In the present invention, the above-mentioned vinyl monomer (b32) is preferably composed of an aromatic vinyl compound and other monomers. Other monomers are preferably vinyl cyanide compounds and maleimide compounds.

When the above-mentioned vinyl-based monomer (b32) contains an aromatic vinyl compound and a vinyl cyanide compound, their total amount is preferably 40 to 100% by mass based on the entirety of the above-mentioned vinyl-based monomer (b32). , More preferably 50 to 100% by mass. In addition, the use ratio of the aromatic vinyl compound and the vinyl cyanide compound is considered from the viewpoints of molding processability, chemical resistance, hydrolysis resistance, dimensional stability, molding appearance, etc., when the total of them is taken as 100. In the case of mass %, it is preferably 5-95 mass % and 5-95 mass %, more preferably 40-95 mass % and 5-60 mass %, and still more preferably 50-90 mass % and 10-50 mass % .

When the above (co)polymer (III-2) is a copolymer, preferred polymers are as follows.

[3-4] Copolymer composed of a structural unit (s) derived from an aromatic vinyl compound and a structural unit (t) derived from a cyanide vinyl compound

[3-5] Copolymerization consisting of a structural unit (s) derived from an aromatic vinyl compound, a structural unit (t) derived from a vinyl cyanide compound, and a structural unit (u) derived from a maleimide compound thing

The production method of the above-mentioned (co)polymer (III-2) is the same as the production method of the above-mentioned (co)polymer (I-2).

The above (co)polymers (III-2) may be used alone or in combination of two or more.

In addition, when the said aromatic vinyl-type resin is a (co)polymer (III-2), the (co)polymer (III-2) described above can be used as it is.

When the above-mentioned aromatic vinyl resin (III) is composed of a rubber-reinforced aromatic vinyl resin (III-1), and when the rubber-reinforced aromatic vinyl resin (III-1) and (co)polymer (III-2) In any case of the mixture configuration, the aromatic vinyl resin (III) is soluble in acetone (wherein, when the rubbery polymer is an acrylic rubber, acetonitrile) The intrinsic viscosity [η] (measured at 30°C in methyl ethyl ketone) of the components is preferably 0.1 to 2.5 dl/g, more preferably 0.2 to 1.5 dl/g, and even more preferably 0.25 to 1.2 dl/g . When the intrinsic viscosity [η] is within the above range, the moldability of the third thermoplastic resin composition is excellent, and the thickness accuracy of the third resin layer is also excellent.

In order to impart sufficient heat resistance to the third resin layer, the aromatic vinyl resin preferably contains a structural unit (u) derived from a maleimide compound. The structural unit (u) may be a structural unit derived from the rubber-reinforced aromatic vinyl resin (III-1) or a structural unit derived from the (co)polymer (III-2). In addition, it may be a structural unit derived from both.

The content of the structural unit (u) for forming the third resin layer excellent in heat resistance is preferably 1 to 40 mass %, more preferably 3 to 40 mass %, based on 100 mass % of the above-mentioned thermoplastic resin (III). 35% by mass, more preferably 5 to 30% by mass. When there is too much content of the said structural unit (u), the flexibility of a 3rd resin layer may fall.

In the present invention, the third resin layer may be a white resin layer having an L value of 60 or more on the surface of a film composed of only a single layer thereof. In addition, the third resin layer may be a low white resin layer having an L value of 1 or more and less than 60 on the surface of the monomer film, a transparent resin layer, or a resin layer colored other than white.

When the above-mentioned third resin layer is a white-based resin layer or a low-white resin layer, the light transmitted through the first resin layer is not sufficiently reflected by the second resin layer, and part of the light is still transmitted through the second resin layer, The light can be reflected by the third resin layer. In the present invention, the third resin layer is preferably a white resin layer.

When the third resin layer is a white resin layer or a low white resin layer, the third thermoplastic resin composition forming the third resin layer is usually a composition containing a white colorant.

Examples of the above-mentioned white coloring agent include titanium oxide, zinc oxide, calcium carbonate, barium sulfate, calcium sulfate, aluminum oxide, silicon dioxide, 2PbCO ₃ ·Pb(OH) ₂ , [ZnS+BaSO ₄ ], talc, Gypsum etc. These colorants may be used alone or in combination of two or more.

In the case where the third resin layer is a white-based resin layer, the content of the white-based colorant is based on the case where light having a wavelength of 800 to 1,400 nm is radiated from the surface of the first resin layer in a solar cell back sheet. Next, from the viewpoint of the light reflectivity on the surface of the first resin layer, it is preferably 1 to 45 parts by mass, more preferably 3 to 40 parts by mass, based on 100 parts by mass of the thermoplastic resin (III). More preferably, it is 5-30 mass parts. When there is too much content of this white coloring agent, the flexibility of the back sheet for solar cells of this invention may fall. In addition, in the said range, when there is little content, by making a 3rd resin layer into a foam layer etc., a white-colored resin layer can be formed.

Moreover, when the said 3rd resin layer is a low-white resin layer, content of the said white coloring agent is preferable with respect to 100 mass parts of said thermoplastic resins (III) from a viewpoint of the reflectivity with respect to the said light. 0.1-5 mass parts, More preferably, it is 0.5-4 mass parts.

It should be noted that, as long as light with a wavelength of 800 to 1,400 nm is radiated to the surface of the first resin layer in the back sheet for solar cells, the reflectance of the light on the surface of the first resin layer is not reduced. The third thermoplastic resin composition may contain other colorants (for example, yellow-based colorants, cyan-based colorants, etc.) depending on the purpose, application, etc. When using another coloring agent, the content is usually 10 parts by mass or less with respect to 100 parts by mass of the above-mentioned thermoplastic resin (III).

The above-mentioned third thermoplastic resin composition may contain additives depending on the purpose, use, and the like. Examples of such additives include antioxidants, ultraviolet absorbers, antiaging agents, plasticizers, fluorescent whitening agents, weather resistance agents, fillers, antistatic agents, flame retardants, antifogging agents, antibacterial agents, antifungal agents, and antifungal agents. agent, antifouling agent, tackifier, silane coupling agent, etc. The specific compounds and their compounding amounts among these additives will be described later.

The thickness of the third resin layer is usually 5 to 500 μm, preferably 8 to 400 μm.

The first resin layer, the second resin layer, and the third resin layer may be continuously stacked (see FIG. 1 ), or between the first resin layer and the second resin layer, between the second resin layer and the second resin layer. An adhesive layer (not shown) for joining the respective resin layers is provided between the layer and the third resin layer. In the latter case, the composition of the adhesive layer may be a polyurethane resin composition or the like.

Next, the thermoplastic resin (IV) contained in the fourth thermoplastic resin composition forming the above-mentioned fourth resin layer (back surface protective layer) is not particularly limited as long as it is a thermoplastic resin. Furthermore, examples of the thermoplastic resin (IV) include saturated polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate; polyethylene, polyethylene Polyolefin resins such as propylene; Fluorine resins such as polyvinyl chloride and ethylene-tetrafluoroethylene copolymers; Polycarbonate resins; Polyamide resins; Polyarylate resins; Polyethersulfone resins; Polysulfone resins; Polyacrylonitrile; Cellulose resins such as cellulose acetate; acrylic resins; aromatic vinyl resins such as polystyrene and ABS resins, etc. These resins may be used alone or in combination of two or more. In addition, among these resins, saturated polyester resins such as polyethylene terephthalate and fluororesins are preferable.

The above-mentioned fourth thermoplastic resin composition may contain additives depending on the purpose, use, and the like. Examples of such additives include coloring agents, antioxidants, ultraviolet absorbers, antiaging agents, plasticizers, fluorescent whitening agents, weather resistance agents, fillers, antistatic agents, flame retardants, antifogging agents, and antibacterial agents. , antifungal agent, antifouling agent, tackifier, silane coupling agent, etc. The specific compounds and their compounding amounts among these additives will be described later.

It should be noted that the above-mentioned fourth resin layer may have a single-layer structure or may have a multi-layer structure. In the latter case, it may be a structure in which films and the like formed of the same composition are laminated, or a structure in which films and the like are formed of mutually different compositions are laminated. Furthermore, a structure in which a layer made of another substance or another composition is formed on one side or both sides of a film or the like made of the above-mentioned fourth thermoplastic resin composition may be used.

The above-mentioned fourth resin layer is preferably a flame-retardant resin layer, and may be a layer derived from a fourth thermoplastic resin composition containing a flame retardant, or may be derived from a composition containing an aromatic ring or a heteroatom in a molecular skeleton. The layer may be a layer in which an organic-inorganic hybrid material is laminated on one side or both sides of a film formed of the above-mentioned fourth thermoplastic resin composition (regardless of the presence or absence of a flame retardant).

The flame retardancy of the above-mentioned fourth resin layer is preferably VTM-2 or higher according to the UL94 standard.

At the time of formation of the said 4th resin layer, the commercial item which is a resin film which has flame retardancy can also be used. For example, "Melinex238" (trade name) manufactured by Teijin Dupont Co., Ltd., "SR55" (trade name) manufactured by SKC Corporation, "Lumira-X10P" manufactured by Toray Corporation, "Lumira-ZV10", "Lumira-X10S", "Lumira- S10", "Lumira-H10", "Lumira-E20" (the above are all trade names), etc.

The thickness of the fourth resin layer is usually 10 to 500 μm, preferably 15 to 400 μm, more preferably 20 to 300 μm. When the above-mentioned fourth resin layer is too thin, the effect of protecting the back sheet for solar cells may not be sufficient. On the other hand, when it is too thick, the flexibility as a board tends to become insufficient.

The above-mentioned first resin layer, the above-mentioned second resin layer, the above-mentioned third resin layer and the above-mentioned fourth resin layer may be in a continuous stacked state (refer to FIG. 1 ), or may have the above-mentioned first resin layer, the above-mentioned second resin layer layer and the third resin layer are continuously stacked, and the third resin layer and the fourth resin layer are bonded via an adhesive layer (not shown). In the latter case, the composition of the adhesive layer may be a polyurethane resin composition or the like.

The solar cell backsheet of the present invention may further include a water vapor barrier layer between the third resin layer and the fourth resin layer as described above.

The above-mentioned water vapor barrier layer is a layer having the following performance: the water vapor transmission rate (also referred to as "water vapor transmission rate") measured under the conditions of a temperature of 40° C. and a humidity of 90% RH based on JIS K7129 is preferably 3 g/(m ² ·day) or less, more preferably 1 g/(m ² ·day) or less, even more preferably 0.7 g/(m ² ·day) or less.

The above-mentioned water vapor barrier layer is preferably a layer made of an electrically insulating material.

The above-mentioned water vapor barrier layer may have a single-layer structure or a multi-layer structure formed of one material, or may have a single-layer structure or a multi-layer structure formed of two or more materials. In the present invention, the vapor-deposited film formed by forming a film made of metal and/or metal oxide on its surface is preferably used as a material for forming a water vapor barrier layer to form a water vapor barrier layer. Both the metal and the metal oxide may be a single substance, or two or more kinds of substances may be used.

The material for forming the water vapor barrier layer may be a three-layer film in which a film made of metal and/or metal oxide is disposed between an upper resin layer and a lower resin layer.

Aluminum etc. are mentioned as said metal.

In addition, examples of the aforementioned metal oxides include oxides of elements such as silicon, aluminum, magnesium, calcium, potassium, tin, sodium, boron, titanium, lead, zirconium, and yttrium. Among these compounds, silicon oxide, aluminum oxide, and the like are particularly preferable from the viewpoint of water vapor barrier properties.

The film formed of the above metal and/or metal oxide can be formed by methods such as plating, vacuum deposition, ion plating, sputtering, plasma CVD, microwave CVD, and the like. It is also possible to combine two or more of these methods.

Examples of the resin layer in the vapor-deposited film include polyester films such as polyethylene terephthalate film and polyethylene naphthalate; polyolefin films such as polyethylene and polypropylene; Vinyl chloride film, polyvinyl chloride film, fluororesin film, polysulfone film, polystyrene film, polyamide film, polycarbonate film, polyacrylonitrile film, polyimide film, etc. The thickness of the resin film is preferably 5 to 50 μm, more preferably 8 to 20 μm.

The above-mentioned water vapor barrier layer can be formed using a commercially available product. For example, films or plates such as "Techbaria AX" manufactured by Mitsubishi Plastics Co., Ltd., "GX Film" manufactured by Toppan Printing Co., Ltd., and "Ecosial VE500" manufactured by Toyobo Co., Ltd. (all of the above are trade names) can be used for forming the water vapor barrier layer. material to use.

The arrangement of the water vapor barrier layer facing the third resin layer is not particularly limited. When a vapor-deposited film is used as the material for forming the water vapor barrier layer, the vapor-deposited film made of metal and/or metal oxide may face the third resin layer, or may be exposed on the outside (surface side). In addition, when the fourth resin layer is provided, the vapor-deposited film may face the fourth resin layer.

The thickness of the water vapor barrier layer is preferably 5 to 300 μm, more preferably 8 to 250 μm, and still more preferably 10 to 200 μm. When the water vapor barrier layer is too thin, the water vapor barrier property may be insufficient. On the other hand, when it is too thick, the flexibility of the solar cell back sheet of the present invention may be insufficient.

When the solar cell backsheet of the present invention includes a water vapor barrier layer, an adhesive layer may be provided between the third resin layer and/or fourth resin layer and the water vapor barrier layer. The composition of the adhesive layer may be a polyurethane resin composition, an epoxy resin composition, an acrylic resin composition, or the like.

The thickness of the solar cell back sheet of the present invention is preferably 50 to 1,000 μm, more preferably 60 to 800 μm, and still more preferably 80 to 600 μm, regardless of the configuration of each layer.

It should be noted that, between the layers in the back sheet for solar cells of the present invention, within the range that does not impair the effect of the present invention, a decorative layer, a coating layer, and a recycled resin produced during production may be laminated as needed. Formed layers and other layers.

In the solar cell back sheet of the present invention, the L value (brightness) on the surface on the fourth resin layer side is preferably 60 or higher, more preferably 65 or higher, and still more preferably 70 or higher.

In the present invention, the thickness (H _A ) of the above-mentioned first resin layer, the thickness of the above-mentioned second resin layer There is a specific relationship between (H _B ) and the thickness (H _C ) of the above-mentioned third resin layer, which is shown below.

0.4≤(H _A +H _C )/H _B ≤2.4 (1)

0.7≤H _A /H _C ≤1.3 (2)

By satisfying the above formula (1), the balance of flexibility and heat resistance in the solar cell back sheet of the present invention is excellent. In the present invention, when (H _A + _HC )/H _B <0.4, the flexibility is poor. On the other hand, when (H _A + _HC )/H _B >2.4, the heat resistance is inferior. It should be noted that, in the present invention, the above formula (1) is preferably 0.5≦( _HA + _HC )/H _B ≦2.2.

In addition, by satisfying the above-mentioned formula (2), the shape stability in the solar cell back sheet of the present invention is excellent. In the present invention, when H _A /H _C <0.7, there is a tendency to curl toward the fourth resin layer side (curl on the first resin layer side) when heat is applied. On the other hand, when H _A /H _C >1.3, when heat is applied, there exists a tendency to curl to the 1st resin layer side (4th resin layer side warpage). It should be noted that, in the present invention, the above formula (2) is preferably 0.75≦ _HA / _HC ≦1.25.

In the present invention, when the thicknesses of the above-mentioned first resin layer, the above-mentioned second resin layer, and the above-mentioned third resin layer are within the above-mentioned preferred range, and the relationship of each thickness satisfies the above-mentioned formulas (1) and (2), due to the The back sheet for solar cells is excellent in shape stability, that is, since the first resin layer side bonded to the above-mentioned filler part is easily bent and warped, it can be efficiently formed according to the surface shape of the filler part in which solar cell elements are embedded. ground configuration board. When the thickness of the second resin layer is increased by omitting the third resin layer, the balance of the layer configuration is insufficient, and it is difficult to obtain the excellent effect of the present invention.

In the present invention, specific examples of the configuration of the solar cell back sheet including the first resin layer, the second resin layer, the third resin layer, and the fourth resin layer are shown below.

[x-1] The first resin layer (infrared-transmitting colored resin layer), the second resin layer (white resin layer), the third resin layer, and the fourth resin layer (rear surface protection layer) are sequentially provided. 3 boards with a white resin layer

[x-2] The first resin layer (infrared-transmitting colored resin layer), the second resin layer (white resin layer), the third resin layer, and the fourth resin layer (rear surface protection layer) are sequentially provided. 3. The resin layer is a board with a low white resin layer

[x-3] The first resin layer (infrared transparent colored resin layer), the second resin layer (white resin layer), the third resin layer, and the fourth resin layer (back protection layer) in this order, the second 3. Boards whose resin layer is a resin layer other than white

[x-4] The first resin layer (infrared-transmitting colored resin layer), the second resin layer (white resin layer), the third resin layer, and the fourth resin layer (rear surface protection layer) are sequentially provided. 3 boards with a colorless and transparent resin layer

In addition, in the present invention, the specific configuration of the solar cell back sheet including the first resin layer, the second resin layer, the third resin layer, the water vapor barrier layer, and the fourth resin layer is shown below.

[y-1] The first resin layer (infrared transparent colored resin layer), the second resin layer (white-based resin layer), the third resin layer, the water vapor barrier layer, and the fourth resin layer (back protection layer) are sequentially provided. layer) and the third resin layer is a white-based resin layer

[y-2] The first resin layer (infrared transparent colored resin layer), the second resin layer (white resin layer), the third resin layer, the water vapor barrier layer, and the fourth resin layer (back protection layer) are sequentially provided. layer) and the third resin layer is a low white resin layer

[y-3] The first resin layer (infrared transparent colored resin layer), the second resin layer (white-based resin layer), the third resin layer, the water vapor barrier layer, and the fourth resin layer (back protection layer) are sequentially provided. layer) and the third resin layer is a resin layer colored other than white

[y-4] The first resin layer (infrared transparent colored resin layer), the second resin layer (white resin layer), the third resin layer, the water vapor barrier layer, and the fourth resin layer (back protection layer) are sequentially provided. layer) and the third resin layer is an uncolored resin layer

In the present invention, when light having a wavelength of 400 to 700 nm is radiated to the surface of the first resin layer in the solar cell back sheet, the absorptivity of the light is preferably 60% or more, more preferably 70% or more, and furthermore Preferably it is 80% or more. The higher the absorptivity, the lower the luminance of the solar cell back sheet, resulting in a dark-colored solar cell back sheet. Accordingly, when the solar cell module is arranged on the roof of a house or the like, it is excellent in appearance and design. It should be noted that "the absorptivity of light with a wavelength of 400 to 700nm is 60% or more" means that the absorptivity of light in the wavelength range of 400nm to 700nm is measured every 20nm from 400nm or 700nm. The calculated average value is 60% or more, and the absorptivity of light in the above-mentioned wavelength range is not required to be 60% or more.

In addition, when light with a wavelength of 800 to 1,400 nm is radiated to the surface of the first resin layer in the back sheet for solar cells, the reflectance of the light is preferably 50% or more, more preferably 60% or more, and even more preferably It is more than 70%. The higher the reflectance, the more light having at least the above-mentioned wavelength can be reflected toward the solar cell element, and the photoelectric conversion efficiency can be improved.

In the present invention, "the reflectance of light with a wavelength of 800 to 1,400nm is 50% or more" means that the reflectance of light in the wavelength range of 800nm to 1400nm is measured every 20nm from 800nm or 1400nm. The calculated average value is 50% or more, and it is not required that all reflectances of light in the above-mentioned wavelength range be 50% or more.

With these properties, in the solar cell back sheet of the present invention, it is preferable that 60% or more of light with a wavelength of 400 to 700 nm is absorbed in the first resin layer, light with a wavelength of 800 to 1,400 nm is transmitted, and at least the second resin layer It sufficiently reflects the light having a wavelength of 800 to 1,400 nm transmitted through the first resin layer, and can be used for photoelectric conversion.

The solar cell back sheet of the present invention is excellent in heat resistance, and the dimensional change rate when the solar cell back sheet is left at 150° C. for 30 minutes is preferably ±1% or less.

The rear surface of the solar cell back sheet of the present invention, that is, the surface of the fourth resin layer is excellent in scratch resistance.

In addition, in the present invention, for the backsheet for solar cells comprising the first resin layer, the second resin layer, the third resin layer, the water vapor barrier layer and the fourth resin layer, water vapor from the side of the fourth resin layer The barrier property is excellent, and when the moisture vapor transmission rate of a solar cell backsheet is measured under the conditions of a temperature of 40°C and a humidity of 90%RH based on JIS K7129, it can preferably be set to 3 g/(m ² ·day) or less , More preferably set to 1 g/(m ² ·day) or less. Due to the above properties, deterioration of the solar cell element due to intrusion of water, water vapor, etc., and further reduction in power generation efficiency can be suppressed, and a solar cell module excellent in durability can be obtained.

Next, additives contained in the above-mentioned first thermoplastic resin composition, second thermoplastic resin composition, third thermoplastic resin composition, and fourth thermoplastic resin composition will be described.

Examples of the antioxidant include hindered amine-based compounds, hydroquinone-based compounds, hindered phenol-based compounds, sulfur-containing compounds, phosphorus-containing compounds, and the like. These compounds may be used alone or in combination of two or more.

The content of the antioxidant is preferably 0.05 to 100 parts by mass of each thermoplastic resin contained in the first thermoplastic resin composition, the second thermoplastic resin composition, the third thermoplastic resin composition and the fourth thermoplastic resin composition. 10 parts by mass.

As said ultraviolet absorber, a benzophenone type compound, a benzotriazole type compound, a triazine type compound, etc. are mentioned. These compounds may be used alone or in combination of two or more.

The content of the ultraviolet absorber is preferably 0.05 parts by mass relative to 100 parts by mass of each thermoplastic resin contained in the first thermoplastic resin composition, the second thermoplastic resin composition, the third thermoplastic resin composition, and the fourth thermoplastic resin composition. ~10 parts by mass.

Examples of the anti-aging agent include naphthylamine compounds, diphenylamine compounds, p-phenylenediamine compounds, quinoline compounds, hydroquinone derivative compounds, monophenol compounds, bisphenol compounds, Triphenol-based compounds, polyphenol-based compounds, thiobisphenol-based compounds, hindered phenol-based compounds, phosphite-based compounds, imidazole-based compounds, nickel dithiocarbamate-based compounds, phosphoric acid-based compounds, etc. These compounds may be used alone or in combination of two or more.

The content of the anti-aging agent is preferably 0.05 parts by mass relative to 100 parts by mass of each thermoplastic resin contained in the first thermoplastic resin composition, the second thermoplastic resin composition, the third thermoplastic resin composition, and the fourth thermoplastic resin composition. ~10 parts by mass.

Examples of the plasticizer include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, dioctyl phthalate, Phthalate esters such as butyloctyl phthalate, di-(2-ethylhexyl) phthalate, diisooctyl phthalate, diisodecyl phthalate, etc. ;Dimethyl adipate, diisobutyl adipate, di-(2-ethylhexyl) adipate, diisooctyl adipate, diisodecyl adipate, octyl adipate Decyl ester, Di-(2-ethylhexyl) azelate, Diisooctyl azelate, Diisobutyl azelate, Dibutyl sebacate, Di-(2-ethylhexyl)decane Fatty acid esters such as dioic acid ester and diisooctyl sebacate; Triesters; Di-(2-Ethylhexyl) Fumarate, Diethylene Glycol Monooleate, Glyceryl Monoricinoleate, Trilauryl Phosphate, Tristearyl Phosphate, Tris-(2 - ethylhexyl) phosphate, epoxidized soybean oil, etc. These compounds may be used alone or in combination of two or more.

The content of the plasticizer is preferably 0.05 parts by mass relative to 100 parts by mass of each thermoplastic resin contained in the first thermoplastic resin composition, the second thermoplastic resin composition, the third thermoplastic resin composition, and the fourth thermoplastic resin composition. ~10 parts by mass.

As the above-mentioned filler, inorganic or organic compounds having spherical (including substantially spherical, polyhedral), fibrous (linear, curved, zigzag) and planar (planar, curved) shapes can be used.

Examples of spherical fillers include wollastonite, talc, kaolin and the like.

Examples of the fibrous filler include inorganic fibers such as glass fibers and ceramic whiskers, and organic fibers such as carbon fibers and aramid fibers.

Mica etc. are mentioned as a planar filler.

The content of the plasticizer is preferably 10 parts by mass relative to 100 parts by mass of each thermoplastic resin contained in the first thermoplastic resin composition, the second thermoplastic resin composition, the third thermoplastic resin composition, and the fourth thermoplastic resin composition. Parts by mass or less.

Examples of the flame retardant include organic flame retardants, inorganic flame retardants, and reactive flame retardants. These flame retardants may be used alone or in combination of two or more.

Examples of organic flame retardants include brominated epoxy compounds, brominated alkyltriazine compounds, brominated bisphenol epoxy resins, brominated bisphenol phenoxy resins, brominated bisphenol polycarbonates Ester resin, brominated polystyrene resin, brominated cross-linked polystyrene resin, brominated bisphenol urea cyanate resin, brominated polyphenylene ether, decabromodiphenyl oxide, tetrabromobisphenol A and its Halogenated flame retardants such as oligomers; trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, tripentyl phosphate, trihexyl phosphate, tricyclohexyl phosphate, triphenyl phosphate Esters, Tricresyl Phosphate, Tris(xylylene) Phosphate, Cresyl Diphenyl Phosphate, Dicresyl Phosphate, Dimethyl Ethyl Phosphate, Methyl Dibutyl Phosphate, Ethyl Dipropyl Phosphate, Phosphate esters such as hydroxyphenyl diphenyl phosphate, compounds modified with various substituents, various condensed phosphoric acid ester compounds, phosphorus-based compounds such as phosphazene derivatives containing phosphorus and nitrogen elements Flame retardants: polytetrafluoroethylene, guanidine salts, organosilicon compounds, phosphazene compounds, etc. These compounds may be used alone or in combination of two or more.

Examples of the inorganic flame retardant include aluminum hydroxide, antimony oxide, magnesium hydroxide, zinc borate, zirconium-based compounds, molybdenum-based compounds, zinc stannate, and the like. These compounds may be used alone or in combination of two or more.

Examples of reactive flame retardants include tetrabromobisphenol A, dibromophenol glycidyl ether, brominated aromatic triazines, tribromophenol, tetrabromophthalate, and tetrachlorophthalic anhydride. , dibromoneopentyl glycol, poly(pentabromobenzyl polyacrylate), chlorendic acid (chloracid), chlorendic anhydride (chloracid), brominated phenol glycidyl ether, dibromocresyl glycidol Ether etc. These compounds may be used alone or in combination of two or more.

The content of the flame retardant is preferably 10 parts by mass relative to 100 parts by mass of each thermoplastic resin contained in the first thermoplastic resin composition, the second thermoplastic resin composition, the third thermoplastic resin composition, and the fourth thermoplastic resin composition. Parts by mass or less.

In addition, when a flame retardant is contained in a thermoplastic resin composition, it is preferable to use a flame retardant adjuvant. Examples of the flame retardant aid include antimony compounds such as antimony trioxide, antimony tetraoxide, antimony pentoxide, sodium antimonate, antimony tartrate, zinc borate, barium metaborate, hydrated alumina, zirconia, Ammonium polyphosphate, tin oxide, etc. These compounds may be used alone or in combination of two or more.

In the present invention, the method for producing a solar cell back sheet having a first resin layer, a second resin layer, a third resin layer, and a fourth resin layer can be selected according to the constituent materials of each layer, that is, each thermoplastic resin composition. , is not particularly limited. The manufacturing method of the board|plate of said aspect [x-1] - [x-4] is shown below.

(1) Coextrusion method using each thermoplastic resin composition.

(2) A method of heat-sealing or dry-laminating four types of resin plates produced using the respective thermoplastic resin compositions.

(3) After producing a laminate composed of the first resin layer, the second resin layer, and the third resin layer by coextrusion, the prepared fourth The method of joining the films of the resin layer.

In addition, the manufacturing method of the back sheet for solar cells provided with the first resin layer, the second resin layer, the third resin layer, the water vapor barrier layer and the fourth resin layer can also be determined according to the layer configuration, the constituent materials of each layer, etc. The selection is not particularly limited. The manufacturing method of the board|plate of said aspect [y-1] - [y-4] is shown below.

(1) By co-extrusion method using the first thermoplastic resin composition, the second thermoplastic resin composition and the third thermoplastic resin composition, etc., a laminated board is produced, and thereafter, heat-welding or dry lamination or bonding The surface of the third resin layer in the laminate is bonded to the sheet (or film) for forming a water vapor barrier layer to form a water vapor barrier layer, and then the fourth thermoplastic resin composition is used to form a water vapor barrier layer. A method of forming a fourth resin layer on the surface.

(2) Using the first thermoplastic resin composition, the second thermoplastic resin composition, and the third thermoplastic resin composition, a laminated board is produced as described above, and then the laminate is laminated by thermal welding or dry lamination or an adhesive The surface of the third resin layer in the sheet is bonded to the sheet (or film) for forming a water vapor barrier layer to form a water vapor barrier layer, and then, the surface of the water vapor barrier layer is additionally heat-welded or dry-laminated or bonded. Adhesive is a method of joining the prepared film using the fourth thermoplastic resin composition.

(3) The film constituting the fourth resin layer and the sheet (or film) for forming a water vapor barrier layer are bonded by heat welding or dry lamination or an adhesive to form a water vapor barrier layer, and thereafter, heat-welded Or dry lamination or adhesive agent, the surface of the water vapor barrier layer and the third laminated board prepared separately using the first thermoplastic resin composition, the second thermoplastic resin composition and the third thermoplastic resin composition A method of bonding resin layers.

The solar cell module of the present invention is characterized by comprising the above-mentioned solar cell back sheet of the present invention. A schematic diagram of the solar cell module of the present invention is shown in FIG. 3 .

The solar cell module 2 of FIG. 3 can be formed by sequentially disposing a surface-side transparent protective member 21, a surface-side sealing film (surface-side filling material portion) 23, A solar cell element 25 , a back side sealing film (back side filler portion) 27 , and a module of the solar cell back sheet 1 of the present invention described above. It should be noted that the solar cell module of the present invention may include various components (not shown) as necessary in addition to the above-mentioned components as necessary.

As the surface-side transparent protective member 21, a member formed of a material excellent in water vapor barrier properties is preferable, and a transparent substrate made of glass, resin, or the like is usually used. Glass is excellent in transparency and weather resistance, but has insufficient impact resistance and is heavy. Therefore, when forming a solar cell mounted on the roof of a house, it is preferable to use a weather-resistant transparent resin. Examples of the transparent resin include fluorine-based resins and the like.

The thickness of the above-mentioned surface-side transparent protective member 21 is usually about 1 to 5 mm when glass is used, and about 0.1 to 5 mm when transparent resin is used.

The solar cell element 25 has a function of generating electricity by receiving sunlight. Such a solar cell element is not particularly limited as long as it has a function as a photovoltaic power source, and known elements can be used. Examples include crystalline silicon solar cell elements such as monocrystalline silicon solar cell elements and polycrystalline silicon solar cell elements; amorphous silicon solar cell elements including single-junction type or random structure type; III-V compound semiconductor solar cell elements such as phosphorus (InP); II-VI compound semiconductor solar cell elements such as cadmium tellurium (CdTe) and copper indium selenide (CuInSe ₂ ), etc. Among these elements, crystalline silicon solar cell elements are preferable, and polycrystalline silicon type solar cell elements are particularly preferable. In addition, thin-film polycrystalline silicon solar cell elements, thin-film microcrystalline silicon solar cell elements, hybrid elements of thin-film crystalline silicon solar cell elements and amorphous silicon solar cell elements, and the like can be used.

Although not shown in FIG. 3 , the above-mentioned solar cell element 25 generally includes wiring electrodes and lead-out electrodes. The wiring electrode has the function of collecting electrons generated in a plurality of solar cell elements by receiving sunlight, for example, to connect the solar cell element on the surface side sealing film (surface side filling material part) 21 side and the back side sealing film ( The solar cell element on the back side side filling material part) 27 side is connected in the form of a solar cell element. In addition, the extraction electrode has the function of extracting electrons gathered by the wiring electrodes and the like to form a current.

The above-mentioned front-side sealing film (surface-side filler portion) 21 and the above-mentioned back-side sealing film (back-side filler portion) 27 (hereinafter, they are collectively referred to as “sealing film”) are usually the same or different from each other. The forming material is formed by forming a plate-shaped or film-shaped sealing film in advance, and then thermocompression-bonding the solar cell element 25 and the like between the above-mentioned surface-side transparent protective member 21 and the solar cell back sheet 1 .

The thickness of each sealing film (filler portion) is usually about 100 μm to 4 mm, preferably about 200 μm to 3 mm, and more preferably about 300 μm to 2 mm. When the thickness is too thin, the solar cell element 25 may be damaged, while when the thickness is too thick, the manufacturing cost becomes high, which is not preferable.

The above-mentioned sealing film forming material is usually a resin composition or a rubber composition. Examples of the resin include olefin-based resins, epoxy resins, polyvinyl butyral resins, and the like. In addition, examples of the rubber include silicone rubber, hydrogenated conjugated diene rubber, and the like. Among these, olefin-based resins and hydrogenated conjugated diene-based rubbers are preferable.

As the olefin-based resin, in addition to olefins such as ethylene, propylene, butadiene, and isoprene, or polymers obtained by polymerizing dienes, copolymers of ethylene and other monomers such as vinyl acetate and acrylate can be used. substances, ionomers, etc. Specific examples include polyethylene, polypropylene, polymethylpentene, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylate copolymer, ethylene-vinyl alcohol copolymer substances, chlorinated polyethylene, chlorinated polypropylene, etc. Among these compounds, ethylene/vinyl acetate copolymers and ethylene/(meth)acrylate copolymers are preferable, and ethylene/vinyl acetate copolymers are particularly preferable.

In addition, examples of hydrogenated conjugated diene rubber include hydrogenated styrene-butadiene rubber, styrene-ethylene-butylene-olefin crystalline block polymer, olefin crystal-ethylene-butylene-olefin crystalline block polymer , Styrene · Ethylene Butene · Styrene Block Polymer, etc. It is preferably a hydrogenated product of a conjugated diene block copolymer having a structure having a polymer block A selected from a unit containing an aromatic vinyl compound; will contain a 1,2-vinyl bond content of more than 25 A polymer block B formed by hydrogenating 80 mol% or more of the double bonds of the polymer of the conjugated diene compound unit in mol%; Polymer block C obtained by hydrogenating 80 mol% or more of the double bond portion of the polymer of the vinyl compound unit; and hydrogenating the double bond portion of the copolymer containing the aromatic vinyl compound unit and the conjugated diene compound unit A block copolymer of at least two types of polymer blocks D formed at 80 mol% or more.

The sealing film forming material may contain a cross-linking agent, a cross-linking auxiliary agent, a silane coupling agent, an ultraviolet absorber, a hindered phenol-based, a phosphite-based antioxidant, a hindered amine-based light stabilizer, Additives for light diffusing agents, flame retardants, anti-tarnish agents, etc.

As mentioned above, the material forming the surface side sealing film (surface side filling material part) 23 and the material forming the back side sealing film (back side filling material part) 27 may be the same or different, but they are preferably the same from the viewpoint of adhesiveness. .

In the solar cell module of the present invention, for example, after sequentially arranging the transparent protective member on the front side, the sealing film on the front side, the solar cell element, the sealing film on the back side, and the solar cell backsheet of the present invention, they can be integrated and carried out by Manufactured by vacuum suction and thermocompression lamination, etc.

The lamination temperature in this lamination method is usually about 100°C to 250°C from the viewpoint of the adhesiveness of the solar cell back sheet of the present invention. In addition, lamination time is about 3 to 30 minutes normally.

Example

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples within the range not exceeding the gist of the present invention. In addition, in the following, parts and % are based on mass unless otherwise specified.

1. Evaluation method

The measurement methods of various evaluation items are shown below.

1-1. Rubber content in thermoplastic resin

The total ratio of all rubber components to the total amount of thermoplastic resin in each resin layer was calculated from the composition when the raw materials for producing the thermoplastic resin composition constituting each resin layer were added.

1-2. N-phenylmaleimide unit content in thermoplastic resin

Calculated from the composition at the time of adding the raw materials for producing the thermoplastic resin composition constituting each resin layer.

1-3. Glass transition temperature (Tg)

Based on JIS K 7121, it is measured with a differential scanning calorimeter "DSC2910" (model name) manufactured by TA Instruments. In addition, when two or more types of thermoplastic resins are contained in a thermoplastic resin composition, and when several Tg is obtained from a DSC curve, a higher Tg is adopted.

1-4. Absorptance (%) for light with a wavelength of 400 to 700 nm

Using a solar cell backsheet (50mm x 50mm, the thickness is listed in the table) as a measurement sample, the transmittance and reflectance were measured with a UV-Vis-NIR spectrophotometer "V-670" (model name) manufactured by JASCO Corporation. Rate. That is, light is irradiated on the surface of the first resin layer of the measurement sample, the transmittance and reflectance in the wavelength range of 400 nm to 700 nm are measured every 20 nm, and their average value is calculated. The absorptance was calculated by the following formula using the average value of the transmittance and the average value of the reflectance.

Absorption (%)=100-{Transmittance (%)+Reflection (%)}

1-5. Reflectance of light with a wavelength of 800 to 1,400 nm (%)

The reflectance was measured with a JASCO ultraviolet-visible-near-infrared spectrophotometer "V-670" (model name) using a backsheet for a solar cell (50 mm x 50 mm, the thickness is described in the table) as a measurement sample. That is, light is irradiated on the surface of the first resin layer of the measurement sample, the reflectance in the wavelength range of 800 nm to 1,400 nm is measured every 20 nm, and their average value is calculated.

1-6. L value

Using the spectrophotometer "TCS-II" (model name) manufactured by Toyo Seiki Co., Ltd., measure the side surface of the first resin layer and the fourth resin in the back sheet for solar cells (50mm x 50mm, the thickness is described in the table) The L value of the side surface of the layer.

1-7. Heat resistance

A back sheet for a solar cell (thickness is described in the table) was cut to prepare a test piece having a size of 120 mm (MD: resin extrusion direction) × 120 mm (TD: direction perpendicular to MD). Next, a square marking line of 100 mm (MD)×100 mm (TD) was drawn on the center of the test piece, and it was left to stand at 150° C. for 30 minutes in a thermostat. Thereafter, it was cooled, and the length in the above-mentioned marked line was measured, and the dimensional change rate was calculated from the following formula.

[number 1]

In addition, the shape of the test piece after processing was observed visually, and it judged by the following reference|standard.

○: No deformation

△: Minimal deformation

×: deformed

1-8. Flexibility

The back sheet for solar cells (the thickness is described in the table) was cut, and the test piece of 100 mm (MD) x 100 mm (TD) size was produced. Next, after bending along the axis of symmetry in the MD direction, it bends along the axis of symmetry in the TD direction. The bent test piece was reciprocated twice on each crease at a speed of 5 mm/sec using a manual pressure contact roller (2,000 g) based on JIS Z 0237. Thereafter, the creases were developed and returned to the original state, and the test piece was visually observed and judged by the following criteria. Those with no creases were excellent in flexibility.

○: The crease is not broken, and the crease is not broken when it is bent and unfolded again.

△: The crease is not broken, but the crease is broken when it is bent and unfolded again.

X: The crease was broken.

1-9. Hydrolysis resistance (maintenance of breaking stress)

The back sheet for solar cells (the thickness is described in the table) was cut, and the test piece of 200 mm (MD) x 200 mm (TD) size was produced. Next, after leaving the test piece at a temperature of 105°C and a humidity of 100%RH for 300 hours, it was cut into a rectangle with a length of 200 mm x a width of 15 mm. Based on JIS K7127, a precision universal material testing machine manufactured by Shimadzu Corporation was used. Autograph AG2000" (pattern name) was used to measure the breaking stress. When fixing the sample for measurement, the distance between the chucks was 100 mm, and the tensile speed was 300 mm/min. From the obtained measured values of the breaking stress, the retention rate of the breaking stress was obtained by the following formula.

Breaking stress retention (%) = (breaking stress (N/15mm) after treatment at a temperature of 105°C and a humidity of 100% RH for 300 hours) ÷ (initial (before treatment) breaking stress (N/15mm))×100

○: The retention rate exceeds 80%

△: The retention rate is 50% to 80%

×: retention rate is less than 50%

1-10. Hydrolysis resistance (determination of deformation state)

The test piece after the high-temperature, high-humidity treatment in the above-mentioned 1-9 was observed visually, and it judged by the following reference|standard.

○: No deformation

△: Minimal deformation

×: deformed

1-11. Photoelectric conversion efficiency improvement rate

In a room adjusted to a temperature of 25 °C ± 2 °C and a humidity of 50 ± 5% RH, the photoelectric conversion of the battery cell was measured in advance using Solar Simulator "PEC-11" (model name) manufactured by Pexel Technology Co., Ltd. A 1/4 polycrystalline silicon cell with a thickness of 3mm is arranged on the surface of the glass, and a solar cell back sheet is placed on the back, and the silicon cell is sandwiched. EVA is introduced between the glass and the solar cell back sheet, and the silicon cell is sealed to make a solar cell module. . Thereafter, in order to reduce the influence of temperature, the photoelectric conversion efficiency was measured immediately after light irradiation. Using the obtained photoelectric conversion efficiency and the photoelectric conversion efficiency of the battery cell, the photoelectric conversion efficiency improvement rate was calculated.

Photoelectric conversion efficiency improvement rate (%)={(photoelectric conversion efficiency of the module-photoelectric conversion efficiency of the battery cell)÷(photoelectric conversion efficiency of the battery cell)}×100

1-12. Heat storage

Taking the backsheet for solar cells (80mm×80mm, the thickness is described in the table) as the measurement sample, in a room adjusted to a temperature of 25°C±2°C and a humidity of 50±5%RH, the first The surface on the resin layer side was irradiated with an infrared lamp (output 100 W) from a height of 200 mm. The surface temperature after 60 minutes of irradiation was measured using a surface thermometer. The unit is °C.

1-13. Weather resistance

The back sheet for solar cells (the thickness is described in the table) was cut, and the test piece of 500 mm (MD) x 30 mm (TD) size was produced. Next, the surface of the test piece on the first resin layer side was subjected to an exposure test by repeating the conditions of steps 1 to 4 shown below, and the color tone change value ΔE before exposure and after 100 hours of exposure was calculated. The processing apparatus was a Metering Waze Meter "MV3000" (model name) manufactured by Suga Testing Instrument Co., Ltd.

Step 1: Irradiate at 0.53kW/m ² , 63°C, 50%RH, 4 hours

Step 2: Irradiation + Rainfall 0.53kW/m ² , 63°C, 95%RH, 1 minute

Step 3: dark 0kW/m ² , 30°C, 98%RH, 4 hours

Step 4: Irradiation + Rainfall 0.53kW/m ² , 63°C, 95%RH, 1 minute

ΔE was calculated by the following formula using Lab (L: lightness, a: redness, b: yellowness) data of a JASCO Spectrphotometer "V670" (model name).

ΔE＝√{(L ₁ -L ₀ ) ² +(a ₁ -a ₀ ) ² +(b ₁ -b ₀ ) ² }

(In the formula, L ₁ , a ₁ , and b ₁ are values after exposure, and L ₀ , a ₀ , and b ₀ are values before exposure.)

The smaller the value of ΔE, the smaller the change in color, indicating that the weather resistance is more excellent. Weather resistance was judged by the following reference|standard.

○: ΔE is 10 or less

×: ΔE exceeds 10

1-14. Flame retardancy

Use the back sheet for solar cells (20mm×100mm, the thickness is described in the table) as the test piece, hang the test piece lengthwise, use the burner for the V test of UL94, and set the distance from the top of the burner to the lower end of the test piece by 10mm. state, the lower end of the test piece was exposed to the flame for 5 seconds. After the flame contact was completed, the combustion state of the flame contact portion of the test piece was visually observed and judged by the following criteria.

○: Not on fire

×: on fire

1-15. Damage resistance

Using a reciprocating motion friction tester manufactured by Tosok Precision Industry Co., Ltd., the surface of the fourth resin layer side in the solar cell back sheet was reciprocated 500 times with cotton canvas bleached cotton cloth (cannequin) No. 3 and a vertical load of 500 g. The surface after visual observation was judged by the following reference|standard.

○: No scratches were observed

Δ: Fewer scratches were observed

×: Obvious scratches were observed

1-16. Water vapor barrier properties

Under the conditions of a temperature of 40°C and a humidity of 90%RH, water vapor permeability was measured based on JIS K7129B using a water vapor transmission rate measuring device "PERMATRAN W3/31" (model name) manufactured by MOCON Corporation. In addition, as a transmissive surface, the surface by the side of the 4th resin layer in the back sheet for solar cells was arrange|positioned at the water vapor side.

2. Raw materials for manufacturing backsheets for solar cells

2-1. Silicone-acrylic composite rubber-reinforced styrene-based resin (rubber-reinforced resin A1)

"Metaburen SX-006" (trade name) manufactured by Mitsubishi Rayon Co., Ltd. was used. It is a resin obtained by grafting acrylonitrile-styrene copolymer on silicone-acrylic composite rubber. The content of silicone-acrylic composite rubber is 50%, the graft ratio is 80%, and the intrinsic viscosity [η] (in methyl ethyl ketone, 30°C) was 0.38dl/g, and the glass transition temperature (Tg) was 135°C.

2-2. Silicone rubber reinforced styrenic resin (rubber reinforced resin A2)

Mix 1.3 parts of p-vinylphenylmethyldimethoxysilane and 98.7 parts of octamethylcyclotetrasiloxane, add it to 300 parts of distilled water in which 2.0 parts of dodecylbenzenesulfonic acid is dissolved, Stir for 3 minutes with a homogenizer to emulsify and disperse. This emulsified dispersion was transferred to a separable flask equipped with a condenser, a nitrogen inlet, and a stirrer, and heated at 90° C. for 6 hours while stirring. Next, it was kept at 5° C. for 24 hours to complete the condensation, and a latex containing a polyorganosiloxane rubber was obtained. The condensation rate was 93%. Thereafter, this latex was neutralized to pH 7 using an aqueous sodium carbonate solution. The obtained polyorganosiloxane rubber had a volume average particle diameter of 300 nm.

Next, 100 parts of ion-exchanged water, 1.5 parts of potassium oleate, 0.01 part of potassium hydroxide, 0.1 part of tert-dodecyl mercaptan, and the polyorganosilicon-containing solution were added to a 7-liter glass flask equipped with a stirrer. A batch polymerization component consisting of 40 parts of oxane rubber latex adjusted to pH 7, 15 parts of styrene, and 5 parts of acrylonitrile was heated while stirring. When the temperature reaches 45°C, add 0.1 parts of sodium ethylenediaminetetraacetate, 0.003 parts of ferrous sulfate, 0.2 parts of sodium formaldehyde sulfoxylate dihydrate, and 15 parts of ion-exchanged water. 0.1 part of benzene hydroperoxide was used to carry out polymerization for 1 hour.

Thereafter, 50 parts of ion-exchanged water, 1 part of potassium oleate, 0.02 parts of potassium hydroxide, 0.1 part of tertiary dodecyl mercaptan, and 0.2 parts of diisopropylbenzene hydroperoxide were continuously added to the above reaction system for 3 hours. parts, 30 parts of styrene and 10 parts of acrylonitrile constitute the incremental polymerization components, and continue to polymerize. After the addition is complete, continue stirring. After 1 hour, 0.2 parts of 2,2'-methylenebis(4-ethyl-6-tert-butylphenol) was added to complete the polymerization, and a silicone rubber-reinforced styrene-based resin (rubber-reinforced resin A2) was obtained. latex. Next, 1.5 parts of sulfuric acid was added to the latex to solidify the resin component at 90° C., and then the resin component was washed with water, dehydrated, and dried to obtain a silicone rubber-reinforced styrene resin (rubber-reinforced resin A2). The glass transition temperature (Tg) is 108°C, the content of polyorganosiloxane rubber is 40%, the graft ratio is 84%, and the intrinsic viscosity [η] (in methyl ethyl ketone, 30°C) is 0.60dl /g.

2-3. Acrylic rubber-reinforced aromatic vinyl resin (rubber-reinforced resin A3)

A solid component containing an acrylic rubber polymer (volume average particle diameter: 100 nm, gel content: 90%) obtained by emulsion polymerization of 99 parts of n-butyl acrylate and 1 part of allyl methacrylate was added to the reactor 50 parts of latex with a density|concentration of 40% (solid content conversion), 1 part of sodium dodecylbenzenesulfonate, and 150 parts of ion exchanged water were added and diluted further. Thereafter, the inside of the reactor was replaced with nitrogen, 0.02 parts of disodium edetate, 0.005 parts of ferrous sulfate, and 0.3 parts of sodium formaldehyde sulfoxylate were added, and the temperature was raised to 60° C. while stirring.

On the other hand, 50 parts of a mixture of 37.5 parts of styrene and 12.5 parts of acrylonitrile, 1.0 parts of terpineolene, and 0.2 parts of cumene hydroperoxide were added to the container, and the inside of the container was replaced with nitrogen to obtain a monomer combination thing.

Next, the above-mentioned monomer composition was added to the above-mentioned reactor at a constant flow rate over 5 hours, and polymerization was performed at 70° C. to obtain a latex. Magnesium sulfate is added to this latex to solidify the resin component. Thereafter, it was washed with water and dried to obtain an acrylic rubber-reinforced aromatic vinyl resin (rubber-reinforced resin A3). The content of the acrylic rubbery polymer is 50%, the graft ratio is 93%, the intrinsic viscosity [η] (in methyl ethyl ketone, 30°C) is 0.30dl/g, and the glass transition temperature (Tg) is 108 ℃.

2-4. Butadiene rubber reinforced aromatic vinyl resin (rubber reinforced resin A4)

Add 75 parts of ion-exchanged water, 0.5 parts of potassium rosinate, 0.1 part of tert-dodecyl mercaptan, and polybutadiene latex (volume average particle diameter: 270 nm, gel content: 90 %) 32 parts (solid content conversion), styrene-butadiene copolymer latex (styrene unit amount: 25%, volume average particle diameter: 550nm, gel content: 50%) 8 parts (solid content conversion), 15 parts of styrene and 5 parts of acrylonitrile were heated up while being stirred in a nitrogen stream. When the internal temperature reached 45° C., an aqueous solution in which 0.2 parts of sodium pyrophosphate, 0.01 part of ferrous sulfate heptahydrate, and 0.2 parts of glucose were dissolved in 20 parts of ion-exchanged water was added. Thereafter, 0.07 part of cumene hydroperoxide was added to initiate polymerization at 70° C., and the polymerization was carried out for 1 hour.

Thereafter, 50 parts of ion-exchanged water, 0.7 parts of potassium rosinate, 30 parts of styrene, 10 parts of acrylonitrile, 0.05 parts of tert-dodecyl mercaptan, and 0.01 parts of cumene hydroperoxide were continuously added for 3 hours, and continued polymerization. After 1 hour of polymerization, 0.2 part of 2,2'-methylenebis(4-ethylene-6-tert-butylphenol) was added to terminate the polymerization to obtain a latex.

Next, magnesium sulfate was added to this latex to coagulate the resin component. Thereafter, it was washed with water and dried to obtain a butadiene rubber-reinforced aromatic vinyl resin (rubber-reinforced resin A4). The content of butadiene rubber was 40%, the graft ratio was 72%, the intrinsic viscosity [η] of the acetone-soluble component was 0.47 dl/g, and the glass transition temperature (Tg) was 108°C.

2-5. Acrylonitrile-styrene copolymer

AS resin "SAN-H" (trade name) manufactured by Techno Polymer Co., Ltd. was used. The glass transition temperature (Tg) was 108°C.

2-6. Acrylonitrile·styrene·N-phenylmaleimide copolymer

Acrylonitrile-styrene-N-phenylmaleimide copolymer "Polyimilex PAS 1460" (trade name) manufactured by Nippon Shokubai Co., Ltd. was used. The N-phenylmaleimide unit amount was 40%, the styrene unit amount was 51%, and the Mw in terms of polystyrene by GPC was 120,000. The glass transition temperature (Tg) was 173°C.

2-7. White coloring agent

Titanium oxide "Taipeku CR-50-2" (trade name) manufactured by Ishihara Sangyo Co., Ltd. was used. The average primary particle size is 0.25 μm.

2-8. Infrared transparent coloring agent

The perylene-based black pigment "Lumogen BLACK FK4280" (trade name) manufactured by BASF Corporation was used.

2-9. Yellow coloring agent

The quinophthalone-based yellow pigment "Paliotol Yellow K0961HD" (trade name) manufactured by BASF was used.

2-10. Carbon black

"Carbon Black #45" (trade name) manufactured by Mitsubishi Chemical Corporation was used.

2-11. Film for Forming the Fourth Resin Layer (Back Protective Layer) (IV-1)

The PET film "Melinex238" (trade name) manufactured by Teijin Dupont Co., Ltd. was used. The thickness is 75 μm.

2-12. Film for Forming the Fourth Resin Layer (Back Protective Layer) (IV-2)

PET film "SR55" (trade name) manufactured by SKC Corporation was used. The thickness is 75 μm.

2-13. Film for Forming the Fourth Resin Layer (Back Protective Layer) (IV-3)

A PET film "Lumira-X10P" (trade name) manufactured by Toray Co., Ltd. was used. The thickness is 50 μm.

2-14. Film for forming a water vapor barrier layer (R-1)

The transparent vapor-deposition film "Techbaria AX" (trade name) manufactured by Mitsubishi Plastics Co., Ltd. was used. It is a transparent film having a silicon dioxide vapor-deposited film on one side of a PET film, has a thickness of 12 μm, and a moisture vapor transmission rate (JIS K7129) of 0.15 g/(m ² ·day).

2-15. Film for forming a water vapor barrier layer (R-2)

The Toyobo Co., Ltd. inorganic two-component vapor deposition barrier film "Ecosial VE500" (trade name) was used. This is a transparent film obtained by vapor-depositing (silica/alumina) on one side of a PET film, with a thickness of 12 μm and a moisture vapor transmission rate of 0.5 g/(m ² ·day).

3. Preparation of the first thermoplastic resin composition

Manufacturing example 1-1

The thermoplastic resin and the colorant were mixed by a Henschel mixer at the ratio shown in Table 1. Thereafter, using a twin-screw extruder "TEX44" (model name) manufactured by Nippon Steel Works, it was melt-kneaded at a barrel temperature of 270° C. to obtain a pellet-shaped first thermoplastic resin composition (I-1) (see Table 1).

Manufacturing Examples 1-2 to 1-7

The first thermoplastic resin compositions (I-2) to (I-7) in the form of pellets were obtained in the same manner as in Production Example 1-1 except that the thermoplastic resin and the colorant were used in the ratio shown in Table 1 (see Table 1 ).

[Table 1]

*1 Content relative to 100% of thermoplastic resin.

4. Preparation of the second thermoplastic resin composition

Manufacturing Example 2-1

The thermoplastic resin and the colorant were mixed by a Henschel mixer at the ratio shown in Table 2. Thereafter, using a twin-screw extruder "TEX44" (model name) manufactured by Nippon Steel Works, it was melt-kneaded at a barrel temperature of 270° C. to obtain a pellet-like second thermoplastic resin composition (II-1) (see Table 2).

Manufacturing Examples 2-2 to 2-8

The second thermoplastic resin compositions (II-2) to (II-8) in the form of pellets were obtained in the same manner as in Production Example 2-1 except that the thermoplastic resin and the colorant were used in the ratio shown in Table 2 (see Table 2 ). In addition, the 2nd thermoplastic resin composition (II-7) is a composition which does not contain titanium oxide, and does not form a white resin layer.

[Table 2]

*1 Content relative to 100% of thermoplastic resin.

5. Preparation of the third thermoplastic resin composition

Manufacturing example 3-1

The thermoplastic resin and the colorant were mixed by a Henschel mixer at the ratio shown in Table 3. Thereafter, using a twin-screw extruder "TEX44" (model name) manufactured by Nippon Steel Works, it was melt-kneaded at a barrel temperature of 270° C. to obtain a pellet-shaped third thermoplastic resin composition (III-1) (see table 3).

Manufacturing Examples 3-2 to 3-6

Except using the thermoplastic resin and the coloring agent in the ratio shown in Table 3, the third thermoplastic resin compositions (III-2) to (III-6) in the form of pellets were obtained in the same manner as in Production Example 3-1 (see Table 3 ).

[table 3]

*1 Content relative to 100% of thermoplastic resin.

6. Manufacture and evaluation of backsheets for solar cells (1)

Example 1-1

The first thermoplastic resin composition (I- 1), the second thermoplastic resin composition (II-1) and the third thermoplastic resin composition (III-1). Then, each resin composition melted at a temperature of 270° C. was discharged from the T-die to form a three-layer flexible film. Thereafter, the surface of the three-layer soft film was brought into close contact with a casting roll whose surface temperature was controlled at 95° C. with an air knife, and cooled and solidified to obtain a laminated film with a thickness of 75 μm. It should be noted that the thicknesses of the first resin layer, the second resin layer, and the third resin layer are as described in Table 4. For the thickness of the film, using the thickness gauge "ID-C1112C" (model name) manufactured by Mitsutoyo Co., Ltd., the film was cut out one hour after the start of film production, and the thickness at the center of the film width direction was measured, and the thickness was measured at 10 mm intervals from the center to both ends. (n=107), take the average value. The value of the measurement point in the range of 20 mm from the edge part of a film is not included in the calculation of the said average value.

Next, the film (IV-1) for forming the fourth resin layer (back surface protective layer) was adhered to the outer surface of the third resin layer in the laminated film using a polyurethane-based adhesive to obtain a solar cell back sheet. Then, various evaluations were performed on this backsheet for solar cells, and the results are shown in Table 4 together.

Examples 1-2 to 1-10 and Comparative Examples 1-1 to 1-9

Using the first thermoplastic resin composition, the second thermoplastic resin composition, and the third thermoplastic resin composition, and a film for forming a fourth resin layer (back surface protective layer), a solar cell back sheet was obtained in the same manner as in Example 1-1. Then, various evaluations were performed on these back sheets for solar cells, and the results are collectively described in Tables 4 to 8.

[Table 4]

[table 5]

[Table 6]

[Table 7]

Comparative Example 1-3 is an example of a solar cell back sheet in which the second resin layer is not a white resin layer, and the growth rate of photoelectric conversion efficiency was as low as 2%.

[Table 8]

7. Manufacture and evaluation of solar cell backsheet (2)

Example 2-1

The first thermoplastic resin composition (I- 1), the second thermoplastic resin composition (II-1) and the third thermoplastic resin composition (III-1). Then, each resin composition melted at a temperature of 270° C. was discharged from the T-die to form a three-layer flexible film. Thereafter, the surface of the three-layer soft film was brought into close contact with a casting roll whose surface temperature was controlled at 95° C. with an air knife, and cooled and solidified to obtain a laminated film with a thickness of 75 μm. It should be noted that the thicknesses of the first resin layer, the second resin layer, and the third resin layer are as described in Table 9. For the thickness of the film, use the thickness gauge "ID-C1112C" (model name) manufactured by Mitsutoyo Co., Ltd., cut out the film after 1 hour from the start of film production, and measure the thickness at the center of the film width direction and at intervals of 10 mm from the center to both ends. The thickness was measured (n=107), and the average value was taken. The value of the measurement point in the range of 20 mm from the edge part of a film is not included in the calculation of the said average value.

Next, the film (R-1) for forming a water vapor barrier layer was adhered to the outer surface of the third resin layer in the laminated film using a polyurethane-based adhesive so that the vapor-deposited film became the outer surface. Further, the film (IV-1) for forming a fourth resin layer (back surface protective layer) was bonded to the surface of the vapor-deposited film in the water vapor barrier layer using a polyurethane-based adhesive to obtain a solar cell back sheet. Then, various evaluations were performed on this solar cell back sheet, and the results are shown in Table 9 together.

Examples 2-2 to 2-10 and Comparative Examples 2-1 to 2-9

Using the 1st thermoplastic resin composition, the 2nd thermoplastic resin composition and the 3rd thermoplastic resin composition, the film for forming a water vapor barrier layer, and the film for forming a 4th resin layer (back protective layer), the same as in Example 2-1 Similarly, a solar cell back sheet was obtained. Then, various evaluations were performed on these back sheets for solar cells, and the results are shown in Tables 9 to 13 together.

[Table 9]

[Table 10]

[Table 11]

[Table 12]

Comparative Example 2-3 is an example of a solar cell back sheet in which the second resin layer is not a white resin layer, and the improvement rate of photoelectric conversion efficiency was as low as 2%.

[Table 13]

Industrial availability

The back sheet for solar cells of the present invention can improve the power generation efficiency of solar cells, and is excellent in designability, heat resistance, flexibility, dimensional stability, and weather resistance, and further, has damage resistance, penetration resistance, and chemical resistance. And flame retardancy is also excellent. Therefore, it is preferable to use outdoors exposed to sunlight and wind and rain for a long time, not only as a solar cell module constituting a solar cell used on the roof of a house, but also as a back sheet in a flexible solar cell module. useful.

Explanation of symbols

1, 1A and 1B: backsheets for solar cells

11: 1st resin layer (infrared transparent colored resin layer)

12: Second resin layer (white resin layer)

13: The third resin layer

14: 4th resin layer (back protection layer)

15: Water vapor barrier layer

2: Solar battery module

21: Transparent protective part on the surface side

23: Surface side sealing film

25: Solar cell components

27: Rear side sealing film

Claims (12)

1. A backsheet for a solar cell, comprising a first resin layer, a second resin layer, a third resin layer, and a fourth resin layer in sequence, wherein the first resin layer is an infrared-transmitting colored resin layer, Among the second resin layer and the third resin layer, at least the second resin layer is a white resin layer, the fourth resin layer is a back protection layer, and the thickness of the first resin layer (H _A ), the thickness (H _B ) of the second resin layer and the thickness (H _C ) of the third resin layer satisfy the following formulas (1) and (2), 0.4≤(H _A +H _C )/H _B ≤2.4 (1) _0.7≤HA / _HC≤1.3 (2). 2. The solar cell back sheet according to claim 1, wherein the thermoplastic resin constituting the first resin layer, the thermoplastic resin constituting the second resin layer, and the thermoplastic resin constituting the third resin layer, Both are thermoplastic resins containing aromatic vinyl resins. 3. The solar cell back sheet according to claim 2, wherein the glass transition temperature of the thermoplastic resin constituting the first resin layer and the glass transition temperature of the thermoplastic resin constituting the third resin layer, All are lower than the glass transition temperature of the thermoplastic resin which comprises the said 2nd resin layer. 4. The solar cell back sheet according to any one of claims 1 to 3, wherein when light having a wavelength of 400 to 700 nm is radiated to the surface of the first resin layer in the solar cell back sheet , the absorptivity for the light is 60% or more. 5. The solar cell back sheet according to any one of claims 1 to 4, wherein light having a wavelength of 800 to 1,400 nm is radiated to the surface of the first resin layer in the solar cell back sheet. In the case of light, the reflectance to the light is 50% or more. 6 . The solar cell back sheet according to claim 1 , wherein the fourth resin layer is a flame-retardant resin layer. 7 . The solar cell back sheet according to claim 1 , further comprising a water vapor barrier layer between the third resin layer and the fourth resin layer. 8 . The solar cell back sheet according to claim 7 , wherein the water vapor barrier layer is formed of a vapor-deposited film formed by forming a film containing metal and/or metal oxide on its surface. 9. The solar cell back sheet according to claim 7 or 8, wherein an adhesive layer is provided between the third resin layer and/or the fourth resin layer and the water vapor barrier layer. 10 . The solar cell back sheet according to claim 1 , wherein the dimensional change rate when left at 150° C. for 30 minutes is ±1% or less. 11 . 11. The solar cell back sheet according to any one of claims 1 to 10, wherein the thickness of the solar cell back sheet is 50 to 1,000 μm. 12 . A solar cell module comprising the solar cell back sheet according to claim 1 .

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